Automatically adjusting headgear for patient interface

ABSTRACT

A headgear for securing a mask to a user&#39;s face is described. The headgear requires a first load force to elongate the headgear and, when fitted to a user, applies a balanced fit force that substantially equals a load force applied to the headgear during respiratory therapy. In some embodiments, the headgear includes an elastic portion configured to provide a retraction force, a non-elastic portion configured to be inelastic in comparison to the elastic portion, and a restriction mechanism connected to the non-elastic portion and to the elastic portion. The restriction mechanism is configured to apply a first resistance force to the user&#39;s head on elongation of the headgear and a second resistance force to the user&#39;s head on retraction of the headgear.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication, are hereby incorporated by reference and made a part of thepresent disclosure.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention generally relates to structures used to securebreathing mask interfaces to a head. More particularly, the presentinvention relates to generally automatically adjusting structures thathave at least one of an adjustment mechanism and a configurationproviding a predetermined wearing length and at least one longer lengthfor donning.

Description of the Related Art

Obstructive sleep apnea (OSA) is a sleep condition in which the back ofthe throat relaxes so much while sleeping that it narrows the airway oreven entirely blocks the airway. With the constriction or closure of theairway, breathing can stop or become very shallow for a few seconds orlonger.

Continuous positive airway pressure (CPAP) is used to treat OSA. CPAPsends a flow of pressurized air that splints open the airway. The flowof pressurized air can be delivered to the user with a breathing maskinterface. The breathing mask interface can include a mask and headgear,such as a non-elastic strap or an elastic strap.

When donning an interface having an elastic strap, the elastic strap isstretched to allow the headgear to slide over the head of the user. Whenreleased, the elastic strap tends to pull the interface against the faceof the user.

When using the elastic strap, as the pressure within the mask increases(e.g., from about 4 cm H2O to about 12 cm H2O), the mask attempts tomove away from the face of the user because the strap securing the maskagainst the face is elastic. The force that attempts to move the maskaway from the face can be defined as the “blow-off force.”

In some masks, when the blow-off force causes the elastic strap tostretch, the force exerted by the mask against the face of the userdecreases. Thus, as pressures increase, leaks can result in those masksand, if suitably sealed at higher pressures (e.g., about 12 cm H2O), theelasticity of the strap causes undesirably high pressures to be exertedagainst the face of the user at lower treatment pressures (e.g., about 4cm H2O) when the pressure is not at the higher pressure level. Aninterface having an adjustable, non-elastic strap can reduce theoccurrence of leaks; however, such headgear are often over-tightenedresulting in unnecessary forces being applied to the user's face and/orhead.

Similar issues can occur in interfaces for treatments other than CPAP.For example, breathing mask interfaces are used in a hospital settingfor non-invasive ventilation (NIV). Generally, NIV provides pressureranges from about 20-50 cmH2O. Thus, the issues described above withrespect to CPAP can be exacerbated in NIV treatment as a result of thegreater difference between lower treatment pressures and highertreatment pressures. Another common respiratory disorder treatment iscalled Bi-level PAP, where the patient experiences an inspiratorypressure (IPAP) and an expiratory pressure (EPAP). The differencebetween IPAP and EPAP can vary from about 1 cmH2O to about 10 cmH2O,which also creates a cyclical blow-off force.

Elastic straps are also commonly used in combination with nasal cannulasfor use in High Flow Therapy (HFT). HFT uses a cannula to deliver a highflow rate of respiratory gases, often including increased oxygenvolumes.

A common problem experienced during the use of nasal cannulas is that ofthe gas supply tube being tugged on, dislodging the cannula prongs fromthe patient's nares, as a result of the headgear stretching. If theprongs are dislodged from the nares then loss of therapy can occur. Evenwithout dislodgment, hose pull on the tube may result in the cannulasitting crooked on the patients face. This may cause discomfort to thepatient and may provide the appearance of reduced effectiveness.Traditionally, cannulas have a lateral horizontal tube connection,which, when there is tension on the tube, can cause the cannula to pullaway from the patient's nares in an uneven manner because the forces aretransferred directly to one side of the cannula.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an interface that willat least provide the industry and users with useful choice.

Some aspects of the present invention relate to providing anauto-adjusting mechanism that secures a breathing mask interface orother types of sealed or substantially sealed interfaces (e.g., nasalpillows) to a face of a user while achieving a balanced fit. As usedherein, “achieving a balanced fit” means that the headgear will applyonly enough force to overcome the “blow-off force” and, in someconfigurations, some or all of the anticipated hose pull forces or otherexternal forces. The “blow-off force” may be defined as the CPAPpressure multiplied by the sealed area of the mask. With auto-adjustingmechanisms that achieve a balanced fit, there will be a minimal forceexerted by the interface mask against the face of the user, whichminimal level of force will maintain a sufficient level of force forsealing of the interface mask against the face of the user. Thus, usercomfort can be increased. Preferably, once the interface assembly isfitted, any adjustments to remedy leaks can be accomplished by gentlywiggling, pushing or pulling the mask interface rather than manipulatingbuckles, clips, straps or the like of the headgear assembly. Whenaspects of the present invention are applied to an unsealed orsubstantially unsealed interface, such as a cannula device, a “balancedfit” is achieved when the length of the headgear cannula loop matchesthe circumference of the user's head and provides some resistance toelongation. Because a cannula system is not pressurized, there is no“blow-off force” therefore the headgear only needs to hold the cannulain place and account for any anticipated hose pull forces. Adjustmentscan be achieved in the same manner as applications used with a CPAP maskor other pressurized or sealed interfaces.

The auto-adjusting mechanism combines some of the benefits of stretchand substantially non-stretch headgear assemblies while, in someconfigurations, removing any need for manual adjustment of the headgearassembly to suit the individual user. As used herein, “manual adjustmentof the headgear assembly” means directly manipulating the headgearassembly to make substantial adjustments to the headgear assembly, suchas a circumferential length defined by the headgear assembly.

Stretch headgear assemblies are known to be easy to fit because thestretch headgear assemblies can be elastically stretched to a lengthrequired to fit over a head of a user and then returned to a shorterlength that fits to a circumference of the head of the user. Non-stretchheadgear assemblies, on the other hand, only apply a minimum forcerequired to secure the interface mask in position, which reduces oreliminates pre-loading that is caused when stretch headgear assembliesremain stretched to some degree while fitting to the circumference ofthe head of the user. In other words, in order to attempt to fit a largerange of head circumferences, stretch headgear assemblies are designedsuch that, if a user has the smallest possible head circumference andthe highest possible CPAP pressure, the stretch headgear assembly willprovide sufficient force to secure the mask interface in position.Unfortunately, such a design will apply a significant force against aface of a user with the largest possible head circumference and thelowest possible CPAP pressure due to the preload that results from theextension of the stretch headgear assembly. For cannula systems, stretchheadgear set ups are traditionally manually adjustable and/or designedto fit the smallest possible head circumference. This can result inmultiple iteration adjustments for users and or tight fits for userswith large head circumferences.

An aspect involves a headgear configured to elongate and retract to fitto a user's head, the headgear requiring a first load force to beapplied to elongate the headgear and the headgear exhibiting a secondload force when the headgear is fit to the user's head and is notelongating.

In some configurations, the first load force is larger than the secondload force and/or an expected load force applied to the headgear duringrespiratory therapy. The expected load force can comprise a combinedforce comprising a CPAP pressure force and a hose drag force. The firstload force can be greater than the expected load force by a reserveamount. The first load force can be greater than the expected load forcethroughout a range of elongation lengths of the headgear and/or thesecond load force can be smaller than the expected load force throughoutthe range of elongation lengths of the headgear.

An aspect involves a headgear for securing a mask to a user's face, theheadgear comprising an elastic portion configured to provide aretraction force, a non-elastic portion configured to be inelastic incomparison to the elastic portion, and a restriction mechanism connectedto the non-elastic portion and to the elastic portion, the restrictionmechanism configured to require a first resistance force to permitelongation of the headgear and a second resistance force in response toretraction of the headgear.

In some configurations, the first resistance force is larger than thesecond resistance force. The first resistance force can be larger than acombined resistance force comprising a CPAP pressure force and a hosedrag force. The second resistance force can be smaller than a combinedforce comprising a CPAP pressure force and a hose drag force.

An aspect involves a headgear configured to elongate and retract to fitto a user's head, the headgear having a first elongation resistanceforce in the absence of radial tensioning and a second elongationresistance force in response to radial tensioning.

In some configurations, the first elongation resistance force is smallerthan the second elongation resistance force. In some configurations, thesecond elongation resistance force is developed by engagement of twoportions of the headgear. The second elongation resistance force can belarger than a combined force comprising a CPAP pressure force and a hosedrag force.

An aspect involves a headgear for securing a mask to a user's face, theheadgear comprising an elastic portion configured to provide aretraction force, a non-elastic portion configured to be inelastic incomparison to the elastic portion, and a restriction mechanism connectedto the non-elastic portion and to the elastic portion, the restrictionmechanism configured to apply an elongation resistance force when theheadgear is radially tensioned.

An aspect involves a patient interface system comprising an interfaceportion sized and shaped to surround the nose and/or mouth of a user andadapted to create at least a substantial seal with a face of the user.The system also includes a coupling that permits the patient interfacesystem to be coupled to a gas delivery system. The system also includesa headgear system that allows the interface portion to be positioned andretained on a head of the user with the headgear system providing atransformational locking behavior with an ability to transform from anelastic type elongation behavior to a generally non-elongating typebehavior when the patient interface system is in use.

In some configurations, the transformational locking behavior isprovided by a mechanically based directional lock.

In some configurations, the headgear system provides the non-elongatingtype behavior in the range of about 0.5N to about 65N

In some configurations, the transformational locking behavior isprovided by a mechanical directional lock that comprises a lockenclosure, a movable lock member and a core member. A cross-sectionaldimension of the core can be in the range of about 0.1 mm to about 8 mm.The lock member can be capable of moving relative to the core memberthrough a range of angles between about 0° to about 45°. A biasingmechanism can act on the lock member and control the lock holding force.The directional lock can incorporate a friction promoter to facilitatelock activation.

In some configurations, the core member is a cord. In someconfigurations, the core member is a strap.

In some configurations, the transformational locking behavior isprovided by a directional lock that uses mechanical adhesion, whereinthe mechanical adhesion is provided through Van der Walls forces byusing a nanofiber material.

In some configurations, the transformational locking behavior isprovided by a directional lock that uses mechanical adhesion, whereinthe mechanical adhesion is provided by a microstructure.

In some configurations, the elastic type elongation is provided by anelastic type elongation system comprising a fabric spring having anintegrated elastic element. The fabric spring can be constructed as abraid where the elastic element and the non-elastic element are combinedin such a manner that the non-elastic element provides a physical endstop to extension before the elastic element is plastically deformed.The amount of elastic element within the braid can be selected toachieve a desired force versus extension property of the fabric spring.

In some configurations, the transformational locking behavior isprovided by a mechanical directional lock that comprises a housing, amovable lock member within the housing and a core member, wherein thehousing guides movement of the core member, and wherein both the housingand the lock member are formed by a single integrated module.

In some configurations, the transformational locking behavior isprovided by a mechanical directional lock that comprises a lock module,a non-elastic portion and an elastic portion, wherein the lock module,the non-elastic portion and the elastic portion form a modularadjustment assembly.

In some configurations, the interface portion is a mask and the modularadjustment assembly is connected to a frame of the mask. The frame cancomprise one or more walls defining a space that receives the lockmodule.

In some configurations, the modular adjustment assembly is connected toa portion of the headgear system. The portion of the headgear system isa rear portion, which can comprise at least one of a lower rear strapand a crown strap.

In some configurations, the headgear system comprises a portion thatpasses on or below the occipital protuberance, which portionincorporates features that provide a non-uniform loading across the rearportion of the head.

In some configurations, the portion that passes on or below theoccipital protuberance comprises an interrupted strap. The interruptedstrap can comprise a first strap section and a second strap sectionconnected by a coupling. The coupling can permit a relative motionbetween the first strap second and the section strap section. Therelative motion can comprise rotational motion about a longitudinal axisof the interrupted strap.

In some configurations, the headgear system can comprise a portion thatpasses above the occipital protuberance, which portion incorporatesfeatures that provide a non-uniform loading across the top portion ofthe head.

In some configurations, the headgear system comprises a portion thatpasses on or above the occipital protuberance, which portionincorporates features that provide a non-uniform loading across thehead.

In some configurations, the headgear system comprises a rear portion andat least one side strap on each side of the interface system thatcouples the rear portion to the interface portion. The at least one sidestrap can be coupled to the rear portion of the headgear system at apoint located forward of and at or near an upper portion of the user'souter ear when in use. The rear portion of the headgear system cancomprise an upper strap and a lower strap, wherein a rearward projectionof the at least one side strap passes between the upper strap and thelower strap. The at least one side strap can comprise a pair of sidestraps arranged in a triangulated configuration.

In some configurations, the transformational behavior is provided by alock mechanism that acts on one or more non-elongating elementscontained within the headgear system to substantially isolate an elasticportion of the headgear system.

In some configurations, the headgear system incorporates a mechanism toenable a range of head sizes to be fitted, the mechanism comprising bothelastic and generally non-elongating elements that are configured inparallel with each other.

In some configurations, the headgear system incorporates a mechanism toenable a range of head sizes to be fitted, the mechanism comprising oneor more generally non-elongating elements substantially encircling theusers head. In some configurations, a first portion of thenon-elongating element overlaps with a second portion of thenon-elongating element in a lengthwise direction of the headgear system.The first portion and the second portion can be first and second ends ofthe non-elongating element. The first portion and the second portion canbe portions of one end of the non-elongating element.

In some configurations, the transformational locking behavior isprovided by a manually operated lock, a pneumatically operated lock, anelectrically operated lock, a piezoelectrically operated lock, ahydraulically operated lock or a thermomechanically operated lock.

In some configurations, the transformational locking behavior has afirst lock stage that provides a first lock force and a second lockstage that provides a second lock force, wherein the second lock forceis greater than the first lock force. In some configurations, the firstlock stage can transform to the generally non-elongating type behaviorwith less elongation movement than the second lock stage.

An aspect involves a headgear for respiratory therapy configured toelongate and retract to fit to a user's head. The headgear requires afirst load force to be applied to elongate the headgear. When theheadgear is fit to the user's head, the headgear provides a balancedretention force that equals a load force applied to the headgear duringrespiratory therapy. The first load force is larger than the balancedretention force.

In some configurations, the load force applied to the headgear duringrespiratory therapy comprises a CPAP pressure force and a hose dragforce. In some configurations, the first load force is larger than theload force applied to the headgear during respiratory therapy by areserve amount. In some configurations, an elastic element applies aretraction force tending to retract the headgear. The retraction forcecan be less than the load force applied to the headgear duringrespiratory therapy.

The term “comprising” as used in the specification and claims means“consisting at least in part of”. When interpreting a statement in thisspecification and claims that includes “comprising,” features other thanthat or those prefaced by the term may also be present. Related terms,such as “comprise” and “comprises,” are to be interpreted in the samemanner.

In this specification where reference has been made to patentspecifications, other external documents, or other sources ofinformation, this is generally for the purpose of providing a contextfor discussing the features of the invention. Unless specifically statedotherwise, reference to such external documents is not to be construedas an admission that such documents, or such sources of information, inany jurisdiction, are prior art, or form part of the common generalknowledge in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages will be described withreference to various embodiments that are arranged and configured inaccordance with certain features, aspects and advantages of the presentinvention, which embodiments are simply used to illustrated but not tolimit the present invention.

FIG. 1 is a perspective view of a user interface useable with headgearthat is arranged and configured in accordance with certain features,aspects and advantages of the present invention.

FIGS. 2A, 2B and 2C are schematic drawings of three phases of headgearfit and adjustment. FIGS. 2D, 2E and 2F illustrate the force profilesassociated with each of the three phases.

FIG. 3A is a schematic drawing of a first phase of headgear fit andadjustment. FIG. 3B illustrates a force profile associated with thefirst phase.

FIG. 4A is a schematic drawing of a second phase of headgear fit andadjustment. FIG. 4B illustrates a force profile associated with thesecond phase.

FIG. 5A is a schematic drawing of a third phase of headgear fit andadjustment. FIG. 5B illustrates a force profile associated with thethird phase. FIG. 5C illustrates detail of FIG. 5B.

FIG. 6 is a graphic illustration of a force profile associated withheadgear having a resistance on demand mechanism.

FIG. 7A is a schematic illustration of one embodiment of headgear havinga resistance on demand mechanism.

FIG. 7B is an illustration of the embodiment of the headgear illustratedin FIG. 7A.

FIGS. 8A and 8B are schematic illustrations of a second embodiment ofheadgear having a resistance on demand mechanism.

FIG. 9 is a schematic illustration of a third embodiment of headgearhaving a resistance on demand mechanism.

FIG. 10 is a schematic illustration of a fourth embodiment of headgearhaving a resistance on demand mechanism.

FIG. 11A is a schematic illustration of a fifth embodiment of headgearhaving a resistance on demand mechanism.

FIG. 11B is a schematic illustration of elongation and retraction of theheadgear shown in FIG. 11A.

FIG. 11C is an illustration of one embodiment of the headgear shown inFIG. 11A.

FIG. 11D is an illustration of a second embodiment of the headgear shownin FIG. 11A.

FIGS. 12A, 12B, 12C and 12D are schematic illustrations of a sixthembodiment of headgear having a resistance on demand mechanism.

FIGS. 13A, 13B and 13C are schematic illustrations of a seventhembodiment of headgear having a resistance on demand mechanism.

FIG. 14 is a graphic illustration of a force profile associated withheadgear having a high resistance to start elongation mechanism.

FIG. 15A is a schematic illustration of one embodiment of headgearhaving a high resistance to start elongation mechanism.

FIG. 15B is a schematic illustration of a second embodiment of headgearhaving a high resistance to start elongation mechanism in a firstposition and FIG. 15C is a schematic illustration of the secondembodiment of headgear having a high resistance to start elongation in asecond position.

FIGS. 16A and 16B are schematic illustrations of a third embodiment ofheadgear having a high resistance to start elongation mechanism.

FIG. 17 is a graphic illustration of a force profile associated withheadgear having a repeated high resistance to elongation mechanism.

FIG. 18A is a schematic illustration of one embodiment of headgearhaving a repeated high resistance to elongation mechanism shown with themechanism resisting elongation.

FIG. 18B is a schematic illustration of the embodiment of headgearhaving a repeated high resistance to elongation mechanism shown in FIG.18A with the mechanism shown allowing retraction.

FIG. 19A is an illustration of the embodiment of FIG. 18A.

FIG. 19B is a second illustration of the embodiment of FIG. 18A.

FIG. 20 is a graphic illustration of a force profile associated withheadgear having a large hysteresis mechanism.

FIG. 21A is a schematic illustration of one embodiment of headgearhaving a large hysteresis mechanism shown with the mechanism allowingfree movement.

FIG. 21B is a schematic illustration of the embodiment of headgear shownin FIG. 21A with the mechanism providing high friction resistance tomovement.

FIGS. 22A, 22B, 22C and 22D are illustrations of one embodiment of theheadgear shown in FIGS. 21A and B.

FIGS. 23A, 23B and 23C are respective schematic illustrations of asecond, third, and fourth embodiment of headgear each having a largehysteresis mechanism.

FIGS. 24A, 24B and 24C are schematic illustrations of a fifth embodimentof headgear having a large hysteresis mechanism. FIG. 24D is a schematicillustration of a headgear in an adjustment phase corresponding to FIG.24A. FIG. 24E is a schematic illustration of a headgear in anapplication phase corresponding to FIG. 24B.

FIG. 25A is a schematic illustration of a sixth embodiment of headgearhaving a large hysteresis mechanism.

FIG. 25B is another schematic illustration of the embodiment of headgearshown in FIG. 25A shown with the mechanism allowing free movement.

FIG. 25C is a third schematic illustration of the embodiment of headgearshown in FIG. 25A shown with the mechanism providing high frictionresistance to movement.

FIG. 26A is an illustration of one embodiment of headgear having a largehysteresis mechanism. FIG. 26B is an illustration of the headgear ofFIG. 26A with the sheath and housings shown in section.

FIG. 26C is an enlarged illustration of a portion of the headgear shownin FIG. 26B.

FIG. 27A is a schematic illustration of a seventh embodiment of headgearhaving a large hysteresis mechanism.

FIG. 27B is an illustration of the embodiment shown in FIG. 27A in aretraction mode.

FIG. 27C is a second illustration of the embodiment shown in FIG. 27A ina mode restricting elongation. FIG. 27D is a graph showing a resistanceforce of the seventh embodiment of headgear.

FIG. 28A is a schematic illustration of an eighth embodiment of headgearhaving a large hysteresis mechanism.

FIG. 28B is an illustration of the embodiment shown in FIG. 28A.

FIG. 28C is a schematic illustration of a ninth embodiment of headgearhaving a large hysteresis mechanism. FIG. 28D is another illustration ofthe ninth embodiment.

FIG. 29A is a schematic illustration of a tenth embodiment of headgearhaving a large hysteresis mechanism. FIG. 29B is a side view of a colletmember of the tenth embodiment of headgear. FIG. 29C is an end view ofthe collet member of FIG. 28B.

FIG. 30 is a graphic illustration of a force profile for headgearallowing adjustment to a loose or tight fit.

FIG. 31A is a graphic illustration of the force applied to the user'shead at various CPAP pressures by a headgear having one of the balancedfit mechanisms described herein.

FIG. 31B is a graphic illustration of the force applied to the user'shead at various CPAP pressures by a headgear without one of the balancedfit mechanisms described herein.

FIG. 31C is a graphic illustration of the difference in force applied tothe user's head at various CPAP pressures between headgear having one ofthe balanced fit mechanisms described herein and headgear without one ofthe balanced fit mechanisms described herein.

FIG. 32 is a partial sectional view of a directional lock utilizing amovable lock member within a lock chamber of a housing and a core memberthat is engaged by the lock member.

FIG. 33 illustrates a partial sectional view of a directional locksimilar to the lock of FIG. 32. The directional lock of FIG. 33 includesa release mechanism that influences a slip force and provides asecondary lock position to the lock.

FIG. 34 is a graph that illustrates a relationship between a lock angleof the lock member and the slip force of a directional lock, such as thedirectional lock of FIGS. 32 and 33.

FIG. 35 is a graph that illustrates a variation in slip force that canresult from variations in the release element in a directional lockhaving a secondary lock position, such as the directional lock of FIG.33.

FIG. 36 is a sectional view of an interface assembly having adirectional lock arrangement utilizing microstructures.

FIG. 37 is an enlarged view of a portion of the interface assembly ofFIG. 36 illustrating two portions of the interface assembly that includemicrostructures.

FIG. 38 is a view of microfibers or nanofibers that can be utilized asthe microstructures in the interface assembly of FIGS. 36 and 37.

FIG. 39 is a view of a plurality of protrusions that can be utilized asthe microstructures in the interface assembly of FIGS. 36 and 37.

FIG. 40 is a side view of a directional lock that utilizes a flat strapand a lock plate carried by a housing. The lock plate is in a releaseposition.

FIG. 41 is a side view of the directional lock of FIG. 40 with the lockplate in a lock position.

FIG. 42 is a sectional view of the lock plate and strap of thedirectional lock of FIG. 40 illustrating an activation mechanism thatenhances engagement between the lock plate and the strap.

FIG. 43 is a perspective view of an interface assembly incorporating atleast one directional lock arrangement being applied to a user.

FIG. 44 is a perspective view of the interface assembly of FIG. 43 in aposition that is closer to a fully fitted position.

FIG. 45 is a perspective view of the interface assembly of FIG. 43fitted to the user.

FIG. 46 is a side view of the directional lock arrangement of theinterface assembly of FIG. 43 in a relaxed position.

FIG. 47 is a side view of the directional lock arrangement of FIG. 46 inan extended position.

FIG. 48 is a side view of the directional lock arrangement of FIG. 46 inan operational position.

FIG. 49 illustrates a portion of a braid that forms an elastic strap ofthe directional lock arrangement of FIGS. 46-48.

FIG. 50 illustrates the braid of FIG. 49 in a compressed position.

FIG. 51 illustrates the braid of FIG. 49 in an extended position.

FIG. 52 illustrates a machine and method for creating the braid of FIG.49.

FIG. 53 is a sectional view of a braid incorporating elastic fibers.

FIG. 54 is a view of the braid of FIG. 53 in a flattened orientation.

FIG. 55 is a rear perspective view of a rear portion of a headgearassembly having an interrupted strap arrangement fitted on a user.

FIG. 56 is a rear perspective view of a rear portion of a headgearassembly having an interrupted strap arrangement fitted on a user, inwhich portions of the strap are coupled by an articulable coupling.

FIG. 57 is a side view of an interface assembly fitted on a user andhaving a side strap between a rear portion of the headgear assembly andthe user interface.

FIG. 58 is a side view of an interface assembly fitted on a user andhaving a pair of side straps between a rear portion of the headgearassembly and the user interface in a triangulated arrangement.

FIG. 59 is a side view of a lock arrangement similar to that of FIGS.46-48, which can form a portion of a modular directional lockarrangement.

FIG. 60 is a perspective view of the lock arrangement of FIG. 59assembled to a mask.

FIG. 61 is a perspective view of a headgear arrangement having anelastic portion and an inelastic portion and defining a complete loop.

FIG. 62 is a top view of the headgear arrangement of FIG. 61.

FIG. 63 is a top view of the headgear arrangement of FIG. 61 in arelatively retracted position.

FIG. 64 is a top view of the headgear arrangement of FIG. 61 in arelatively extended position.

FIG. 65 is a top view of the headgear arrangement of FIG. 61illustrating a first example placement for directional locks.

FIG. 66 is a top view of the headgear arrangement of FIG. 61illustrating a second example placement for directional locks.

FIG. 67 is a perspective view of a headgear arrangement having anelastic portion and an inelastic portion and defining an interruptedloop.

FIG. 68 is a top view of the headgear arrangement of FIG. 67.

FIG. 69 is a top view of the headgear arrangement of FIG. 67 in arelatively retracted position.

FIG. 70 is a top view of the headgear arrangement of FIG. 67 in arelatively extended position.

FIG. 71 is a top view of the headgear arrangement of FIG. 67illustrating a first example placement for directional locks.

FIG. 72 is a top view of the headgear arrangement of FIG. 67illustrating a second example placement for directional locks.

FIG. 73 is a graph that illustrates force profiles for CPAP balancedfit, cannula balanced fit, high force elastic strap and low forceelastic strap relative to a CPAP operating envelope.

FIG. 74 is a partial sectional view of a multi-stage directional lock.

FIG. 75 is a graph illustrating a force profile of a multi-stagedirectional lock.

FIG. 76 is a graphical illustration of forces involved in certain typesof respiratory therapy involving a sealed patient interface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference initially to FIG. 1, an interface assembly 100 isillustrated. The interface assembly 100 can have any suitableconfiguration. The illustrated interface assembly 100 is a nasal maskbut, in some configurations, certain features, aspects and advantages ofthe present invention can be used with any type of interface, includingbut not limited to full face masks, nasal masks, nasal pillows,nasal-oral masks, oral masks and cannulas.

The illustrated interface assembly 100 generally comprises a frame 102that supports a seal 104. The frame 102 and/or the seal 104 can beconnected to a supply conduit 106. In some configurations, the supplyconduit 106 can be connected to the frame with an elbow 110. The supplyconduit 106 can be used to supply breathing gases to a user through theseal 104. The seal 104 or a combination of the seal 104 and the frame102 can define a chamber that receives the breathing gases from thesupply conduit 106.

The interface assembly 100 comprises mounting points 112. The mountingpoints 112 can be formed on at least one of the frame 102, the seal 104,the conduit 106 and the elbow 110. Any suitable mounting points 112 canbe used to facilitate connection between the interface assembly 100 andone or more headgear assembly, which will be described below. In someconfigurations, the mounting points 112 facilitate easy connection anddisconnection of the headgear assembly and the interface assembly 100.In some configurations, the headgear assembly and the interface assembly100 can be joined together such that the headgear assembly is notgenerally removable from one or more component of the interface assembly100. In some configurations, the headgear assembly and the interfaceassembly 100 can be integrally formed.

With reference to FIG. 76, a graphical illustration 2300 is provided tofacilitate a description of forces involved in certain types of positivepressure respiratory therapy using a sealed patient interface. Withrespect to patient interfaces that seal on the face of the user, theinterface (e.g., mask) in cooperation with the user's face creates asealed chamber, as indicated in block 2302. Pressurized breathing gasesare delivered to the sealed chamber, which generates a force tending tomove the mask away from the user's face. This force is generally equalto the (projected) seal area multiplied by the positive pressure and isoften referred to as the “blow-off” force, as indicated in block 2304. Afunction of the headgear is to restrain the mask in response to theblow-off force to keep the mask in equilibrium sealed against the faceof the user, as indicated in block 2306. As indicated in block 2308, theblow-off force stresses the headgear in an attempt to elongate it, whichplaces the headgear under tension. In addition, as indicated in block2310, the headgear applies a force to the user's head over an area withwhich the headgear is in contact. The force applied to the contact areacan be referred to as the “skin pressure” of the headgear. As the airpressure within the chamber defined by the seal 104 or the combinationof the seal 104 and the frame 106 increases, the force applied by theheadgear attempts to restrain the interface assembly 100 from liftingfrom the face. As such, the force applied by the headgear generally willincrease to oppose the increasing force resulting from the increasingpressure within the mask. The blow-off forces will vary for differenttypes and sizes of interfaces at any given pressure. Nevertheless, atlower pressures, or no pressure in the case of cannulas, less force isrequired to oppose the blow-off forces.

Accordingly, and as will be explained, the headgear assemblies describedherein preferably can be designed to achieve a “balanced fit.” In someconfigurations, the headgear assemblies generally comprise a stretchcomponent (also referred to as elastic), a non-stretch component (alsoreferred to as inelastic or non-elastic), a mechanism that restrictsextension of the headgear, and a coupling that can join the headgearassembly to the mounting points 112, for example but without limitation.In at least some configurations, the balanced fit can be achieved bycreating a substantially non-stretch path to resolve the stresses in theheadgear when in use or in response to normal operational forces (e.g.,blow-off and/or hose pulls forces, plus a reserve, if desirable). Athigher forces than seen in use, the headgear can exhibit stretch-likebehavior for donning. In some configurations, the headgear assembly maynot include a stretch component. For example, the headgear could bemanually extended and retracted. Various embodiments of the headgearwill be described below.

The stretch components, when present, can have any suitableconfiguration. The stretch components can be any component that has atensile modulus of less than about 30 MPa. The tensile modulus is themathematical description of the tendency to be deformed elastically(i.e., non-permanently) along an axis when forces are applied along thataxis; tensile modulus is the ratio of stress to corresponding strainwhen a material behaves elastically. In some configurations, the stretchcomponent can be a coated, spun yarn material and the stretch componentcan include materials such as, but not limited to, rubber and spandex orelastane (e.g., LYCRA). In some configurations, the stretch componentcan be a strap or a combination of straps. In some configurations, thestretch component can be formed of a stretchable or elastic material. Insome configurations, the stretch component enables the headgear to beexpanded or lengthened and the stretch component also provides aretraction force that serves to contract or shorten the headgear. Thecontraction, or shortening, can occur as a result of the elasticproperties of the stretch component. The contraction, or shortening,allows the headgear to more closely match the user's head circumference(plus the size of the mask). Generally, the headgear length is definedby a relaxed length and the headgear seeks to return to that length andit is this returning toward the relaxed length after elongation that ismeant by contraction unless otherwise apparent.

The non-stretch components can serve as a stretch limiter. Thenon-stretch components can have any suitable configuration. In someconfigurations, the non-stretch components have a higher modulus ofelasticity compared to the stretch components. The stretch componentscan be any component that has a tensile modulus of more than about 30MPa. In some configurations, the non-stretch components restrictelongation of the headgear due to forces that are lower than a specifiedyield force. In some configurations, the yield point of the non-stretchmaterial is higher than any anticipated loading to be applied to theheadgear. In some configurations, the non-stretch components resistelongation of the headgear once the headgear has been fitted to thehead. In some configurations, the non-stretch components resistelongation of the headgear once the headgear has been fitted to the headand the CPAP pressure has been applied to the mask. Thus, in someconfigurations, the non-stretch components (in some cases, incombination with the mechanisms discussed below) can thwart or resistelongation of the stretch components at least when CPAP pressure isapplied. In the case of a cannula, the non-stretch components can resistthe movement of the cannula under the influence of external forces, suchas hose pull.

The mechanism can be any suitable mechanism that can limit expansion orelongation of the headgear when a force lower than a specified yieldforce is applied to the headgear. In some configurations, the mechanismoperates without an effort by the user (e.g., the mechanism isautomatic). That is, in at least some configurations, the mechanism canautomatically move or switch to a mode in which extension or expansionis limited below the specified yield force. However, effort may berequired for the user to don the mask, such as effort above the yieldforce to extend the headgear. In some configurations, the mechanism canapply a motion resistance force that can limit the extension orexpansion of the headgear when a force lower than the specified yieldforce is applied to the headgear. In some such configurations, themotion resistance force can be a friction force. The specified yieldforce, that is, the force at which the headgear mechanism's motionresistance forces are overcome and elongation of the headgear becomespossible, may be determined by (1) the maximum blow-off force that ispossible for the specific mask in use when a range of about 4-20 cmH2Opressure is anticipated and (2) a reserve to allow for any pulling ofthe CPAP hose and differences in user fit preferences. The reserve,generally defined as the difference between the lengthening or extensionforce and the maximum balanced fit force, can provide a buffer above thebalance fit force, in which additional forces can be applied to theheadgear without substantial elongation of the headgear occurring. Thereserve force component can compensate for any additional force, such ashose pull, that may act to pull the headgear from the user's head. Insome configurations, the motion resistance force can be applied torestrict extension of the headgear while releasing to allow retractionor contraction of the headgear. In some configurations, the mechanismcan use one-way friction to lock or otherwise secure the headgearlength. For example, the length can be secured using a frictional forcethat can only be overcome by a force that exceeds the blow-off forcewith minimal extension. Such mechanisms can be referred to herein as adirectional locking arrangement or directional lock. The term “lock” asused herein is intended to cover mechanisms that secure the headgearlength in response to certain forces, such as blow-off forces and/orhose pull forces. A “lock” does not necessarily secure the headgearlength in response to all forces. Preferably, in some configurations,the retention force of the lock (“lock force”) can be overcome, such asby manually-applied forces during the application portion of the fitmentprocess.

As described above, the headgear can be stretched or extended to allowthe mask to be fitted around the head of the user. The mechanism, whileallowing the stretching or elongation of the headgear, also provides ameans for locking the length of the headgear so that, when the CPAPpressure is applied, the seal is generally held in place and theheadgear does not elongate substantially. In some configurations, asmall amount of elongation may occur while the mechanism engages.

In some configurations, one-way friction headgear can incorporate amechanism that is designed to give the user all the benefits ofnon-stretch headgear with the same ease of use experience as existingstretch headgear with little to no manual adjustment.

Stretching of the elastic headgear is typically not helpful inmaintaining a seal. A mask that seals on the face will always result ina blow-off force and in turn a reaction force in the headgear. Thisforce will stretch the headgear, affecting the fit of the seal. Astretching headgear must therefore be over-tightened to anticipate andcompensate for this change, resulting in an unbalanced fit at lowerpressures if a balanced fit is obtained at higher pressures withoutadjustments being made to the headgear.

The one-way friction mechanism can stop the non-stretch strap componentof the headgear from changing its length when the seal is established.Once the CPAP machine is turned on and the seal is established, eachuser's variables, such as fit preference, face shape, etc. will createblow-off forces that attempt to push the mask away from the user's face.This blow-off force may be countered by a one-way friction mechanismthat reduces or eliminates the likelihood of the non-stretch strapchanging its length, resulting in a balanced fit over a range ofpressures.

A mask that is sealed against the face is essentially a pressure vessel.The mask needs to be held against the face to maintain the airtightnessand create a seal. The absolute minimum force required equals the(projected) seal area multiplied by the positive pressure. This force isthe blow-off force as the direction points away from the face. Tobalance this force is the primary function of the headgear. A balancedfit is achieved when the reaction forces in the headgear substantiallymatch the blow-off force. In a cannula embodiment, generally there is noseal between the patient and the cannula and thus there is no blow-offforce. A balanced fit therefore can be achieved when the headgearassembly circumference matches the user's head circumference and providesome resistance to elongation or extension. For a cannula system, theself-fit headgear, as described herein, allows for a quick and easy fitwithout over tightening and excessive forces, which can occur withmanually adjusted and elasticated headgears, respectively.

The projected seal area (even at the same given pressure) varies fromperson to person and depends on facial features and personal fitpreferences. Consider the difference between a smooth-faced person and amore ‘weathered’ face. It is likely easier to make a seal on a smoothface, resulting in a smaller seal area and a lower correspondingblow-off force. Similarly, on the same person, at the same pressure, aseal can be made and maintained with a different fit, such as either aloose or tight fit. This is especially true with a mask having aninflatable seal. A loose fit will result in a smaller area andcorresponding lower blow-off force.

With a balanced fit, the forces between the headgear and the user's headwill be equal to the amount of force required to achieve the seal. CPAPfeatures that vary the pressure throughout the night to give comfort tothe user can complicate the situation when using standard headgeardesigns. The variations in pressure throughout the course of the nightalter the amount of blow off force throughout the night. With headgearincorporating a balanced fit mechanism, the reaction forces drop in syncwith the reducing CPAP pressure.

Hose pull is an additional force that is caused by the CPAP or cannulahose dragging when the user changes sleeping position. The hose draggingforces temporarily increase the force on the headgear. If the forceexceeds the mechanism's resistance to elongation the fit will changewhich may result in leakage and/or discomfort.

As a user changes sleeping position while wearing the headgear describedbelow, the headgear fit may be required to change. At this point, thenatural interaction of pushing or wiggling the seal toward the face willresult in the strap automatically retracting any excess length tomaintain the new fit. In some situations, the mask or the seal may bepulled away from the face to cause the headgear to increase in length.

To remove the interface while wearing the headgear described below, theseal can be pulled forward with a force greater than the mechanism'smaximum holding force. This causes the headgear to lengthen and whichenables the seal to be pulled away from the face and over the user'shead. Once removed, the lack of forces on the headgear will cause theheadgear to automatically retract to its relaxed size.

In some configurations, the headgear applies a three phase forceextension fit profile, an overview of which is shown in FIGS. 2A-2C. Inthe application phase 200, the headgear is stretched to go over the headof a user. The graph illustrates a resistance during elongation. Theload curve 202 illustrates a steep rise in load for the initialextension of the headgear that then transitions to a generally constant,flat extension curve as the headgear is further stretched to accommodatelarger head circumferences. In the adjustment phase 204, the headgearretracts and returns from a stretched condition until a desired fit isachieved. The load curve 206 shows an initial decrease in load as theheadgear retracts to fit onto the user's head and also illustrates a lowload force as the headgear further retracts to fit the user's headcircumference. In the third phase, the balanced fit phase 208, theheadgear adjusts to hold its position on the user's head as CPAPpressure is applied. The load curve 210 illustrates that a rise in loadforce of the headgear balances with the blow-off force due to the CPAPpressure and also resists additional forces, such as hose pull. In thecase of a cannula embodiment, a balanced fit can be achieved at the endof phase two, and phase three typically will only be initiated if andwhen an external force, such as hose pull, is experienced. Furtherdetail of the components of the balanced fit will be discussed below.

With reference now to FIGS. 3A-3B, additional detail of the applicationphase 200 and the related load curve 202 is shown. As discussed above,the load curve 202 illustrates a steep rise 220 because the headgear hasinitial resistance to stretch as it is stretched to accommodate theuser's head. The initial resistance can relate to overcoming theresistance that will resist elongation. Once the load has reached ayield force of the mechanism of the headgear, the load curve transitionsto a substantially flat, generally constant extension curve 222 as theheadgear stretches further with little increase in load force forgreater amounts of headgear extension.

FIGS. 4A-4B illustrate the second phase, or adjustment phase 204, ingreater detail. In this phase, the headgear has been sufficientlystretched or elongated to fit over the user's head and the headgear hasbeen released into position. Once a desired positioning has beenachieved, the headgear returns from the stretched condition (e.g.,over-elongated position) and the load force sharply declines 224, asshown in the load curve 206. After this reduction in force due toretraction of the headgear to fit the user's head, the load curveremains low 226 as the headgear remains fitted to the user's head. Asillustrated, the headgear that typifies many features, aspects andadvantages of the present invention features a first high load requiredto cause elongation and a second lower load at which the headgearcontracts. In other words, the headgear contracts at a lower load thanrequired to cause elongation and a hysteresis is the provided effect. Insome configurations, the headgear has a delay in length change while theforce changes dramatically when changing from an elongation mode to acontraction mode. In some configurations, the change in length of theinterface circumference (including the headgear assembly) lags behindchanges in load (i.e., force) when the interface length changes fromelongation to contraction. Moreover, in some configurations, duringelongation, as the force increases, the length increases more than thedecrease in length during the decrease in force (e.g., the slope islower at 220 than at 224).

In FIGS. 5A-5C, a balanced fit is achieved in the balanced fit phase208, in which the force of the headgear balances the blow-off force ofthe CPAP pressure. As mentioned above, the headgear adjusts to hold itslength as CPAP pressure is applied. The load curve 210 illustrates therise in the load force that balances the blow-off force. As shown in thedetailed balanced fit section 230 of the load curve 210, the balancedfit produces a higher load than the retraction force 226 of theheadgear. The balanced fit component is the increasing force in thestrap of the headgear that provides an equal and opposite force to theblow-off force. However, this force is also lower than the lengtheningor extension curve 222. In some configurations, the slope of thebalanced fit section 230 is related to, influenced by, or can besubstantially the same as the rise 220 and/or the decline in the loadforce 224 during retraction of the headgear. In some configurations, theslope of the balanced fit section 230 is steeper than the slope in thedecline in the load force 224. In some configurations, the slope of thebalanced fit section 230 is greater than the slope in the initial rise220 during lengthening of the headgear.

A reserve force component 232, defined as the difference between thelengthening or extension force 222 and the instantaneous or currentbalanced fit force 234, is a buffer above the balance fit force, inwhich additional forces can be applied to the headgear withoutsubstantial elongation of the headgear occurring. The reserve forcecomponent can compensate for any additional force, such as hose pull,that may act to pull the headgear from the user's head. As externalforces, such as hose pull, rise so do the reaction forces in theheadgear. Only if the external forces surpass the yield point will theheadgear elongate, which can result in leaks. The reserve componentpreferably is large enough to accommodate a realistic external forcethat could be applied to the mask by the hose being pulled on duringnormal use. This reserve component or buffer also allows for the user'spreference in engagement of the seal of the mask with the user's face,such as a tighter or looser fit. When used with a cannula system, thewhole of phase three can be allocated to reserve force. Because there isno blow-off force, a balanced fit can be achieved at the end of phasetwo and, thus, phase three typically only needs to account for anyexternal forces, such as hose pull, and user preference in terms oftightness of fit. As a result, the yield force for a cannula set-up canbe substantially lower than for a CPAP set-up. In general, the forcewithin the headgear when a balanced-fit is achieved can also be lowerfor a cannula set-up than a CPAP set-up.

The graphs of FIGS. 3-5 also include a perimeter that surrounds anddefines an area. The illustrated perimeter is generally rectangular inshape and represents an operating envelope of an interface assembly asit relates to head circumference of the user (extension) and forceapplied by the CPAP system (load), which could, but does notnecessarily, include external forces, such as hose pull. A length of thearea along the x-axis or a distance between a left end 212 and a rightend 214 of the perimeter represents the desired or usable range of userhead size. That is, the left end 212 is located at a lower head size(circumference or extension) and the right end 214 is located at anupper head size. The lower and upper head sizes can be minimum andmaximum head sizes for a particular interface assembly, which can be auniversal fit or intended for a certain subset of head sizes (e.g.,small, medium, large) or users (e.g., infant, adult).

A length of the area along the y-axis or a distance between a lower end216 and an upper end 218 of the perimeter represents the desired orusable range of force or load that is applied the interface assembly inuse. The lower end 216 of the perimeter is located at a lower force(e.g., force resulting from a low CPAP value) and the upper end 218 ofthe perimeter is located at an upper force (e.g., force resulting from ahigh CPAP value). As with head sizes, the lower and upper forces can befor CPAP systems or protocols in general or can be for a specific subsetof CPAP systems or protocols. As described above, the force range can bebased on CPAP forces alone, or can include external forces, such as hosepull forces, for example. Preferably, the instantaneous or currentbalanced fit force 234 falls within the operating envelope.

For a stretch or elastic system to offer sufficient performance acrossthe operating envelope, the system must provide a greater resistanceforce than the interface assembly can generate via one or both of CPAPpressure forces and external forces. Thus, the force-extension curve ofthe stretch or elastic system should be positioned above the operatingenvelope and, if necessary, spaced above the operating envelope by adistance sufficient to address external forces and/or provide a reserveto address unusual or unexpected forces. Accordingly, stretch or elasticsystems apply a force to the user that is at a greater level thannecessary to address the actual forces applied to the interface assembly(e.g., CPAP and external forces). This greater-than-necessary forcetends to result in reduced comfort for the user.

Different force profile configurations are possible for the headgearassembly, with the force profile configurations preferably including abalanced fit region. The force profiles described herein are applicableto both CPAP and cannula systems; however, the point at which a balancedfit is achieved will usually differ. The force levels associated withmaintaining the fit of the interface generally will also besignificantly lower in cannula systems. In addition, some or all of theheadgear embodiments will work, or could be modified to work, for acannula system wherein a balanced fit is achieved when the headgearcircumference matches the head circumference and, preferably, someamount of resistance to extension of the headgear is provided.Increasing CPAP pressure and/or blow-off forces generally will correlateto an external force being applied to a cannula system. FIG. 6illustrates one force profile 240 in which resistance of the headgearstrap results on demand. This configuration requires the least effort toextend and fit the headgear. In this configuration, the user only has toovercome the elasticity of the headgear, as illustrated by curve 242,which typically requires a force of less than about 1.5N. The balancedfit component of this configuration, illustrated by the curve 244,provide an equal and opposite force to the blow-off force and alsocompensate for any additional external forces that may act to pull theheadgear from the user's head. The curve 246 adds a buffer in additionto the balanced fit portion 244.

FIGS. 7A-B illustrate one embodiment of headgear that has the resistanceon demand profile shown in FIG. 6. The illustrated configurationcomprises a layered stretch assembly 304. In the layered stretchembodiment 304 shown in FIG. 7A, two straps 306 and 308 can be layered,one on top of the other, each with alternating stretch 310, 316, 320 andnon-stretch 312, 314, 318 sections. As shown, the two straps 306 and 308may be folded over one another, as indicated by the arrow 324 such thatthe non-stretch section of one strap overlaps with at least the stretchsection of the other strap. As shown, the non-stretch segment 314 of thestrap 306 overlaps the stretch segment 316 of the strap 308. Thenon-stretch segment 314 is preferably longer than the stretch segment316 such that at least a portion of the non-stretch segment 314 overlapswith at least a portion of the non-stretch segment 312 to create acontinuous non-stretch path. Similar overlap of the non-stretch segment312 with the non-stretch segment 318 is also shown. In addition, thestraps 306 and 308 can have a form of “grip,” such as rubber webbing orother tacky substance, on the non-stretch sections. When positioned ontop of each other as indicated by the overlapping grip section 322, thegrip sections overlap and catch, reducing or eliminating the likelihoodof further elongation of the headgear straps until the motion resistanceforce between the straps is exceeded. Once the headgear is placed on theuser's head, the radial force between the stretch and non-stretch layerscauses the grip sections to engage and form a complete non-stretchsection, limiting further elongation of the headgear straps. FIG. 7Bshows two photographs of the layered strap embodiment shown in FIG. 7A.

Another embodiment of a layered stretch strap configuration is shown inFIGS. 8A and 8B. The layered grip strap configuration 400 is composed oftwo straps, one having a grip pattern in one or more locations, and theother strap having a series of alternating stretch segments or sections414 and non-stretch segments or sections 412, 416, as in theconfiguration shown in FIG. 7A. Although one stretch and two non-stretchsegments are illustrated, other numbers of stretch and non-stretchsegments could be provided. A first or inner strap 406 is shown with twogrip pattern segments 410 located on either end of the strap 406;however, different numbers of grip pattern segments 410 can be provided,including a grip pattern along substantially an entire length of thestrap 406. The grip segments 410 overlap with the non-stretch segments412, 416 of a second or outer strap 408 to provide an interactivegripping section that selectively couples at least a portion of thestraps 406, 408. However, this arrangement could also be reversedbetween the inner strap 406 and the outer strap 408. In someconfigurations, the inner strap 406 is a non-stretch member, whichallows the headgear to form a complete non-stretch section when thestraps 406, 408 are coupled, limiting further elongation of theheadgear, as discussed above. However, in other configurations, theinner strap 406 can be constructed from an elastic or stretchablematerial. In such configurations, the headgear includes a stretchsection even when the straps 406, 408 are coupled, a length of which canbe defined by the elastic portion 414 of the outer strap 408.Preferably, the stretch section is provided at the back of the user'shead and non-stretch sections are located on the sides of the user'shead. Positioning the stretch section at the back of the user's head canresult in less stretch movement for a given force than a stretch sectionprovided on the side of the user's head. When the headgear is loaded,such as a result of blow-off forces or external forces, the section ofat the back of the user's head is pulled against the user's head therebyincreasing friction between the headgear and the user's head. In someconfigurations, the friction can be sufficient to substantially preventstretch movement of the stretch section of the headgear. Features toenhance friction between the headgear and the user's head can beemployed, such as silicone or other types of grip elements, for example.The stretchable inner strap 406 can facilitate stretching of theheadgear prior to donning. In some configurations, such as when asubstantial entirety of the inner strap 406 is stretchable, the materialof the section(s) 414 of the outer strap 408 has a substantially lowerelongation modulus compared to the material of the inner strap 406 toaddress the length of the stretch section(s) 414 being substantiallyless than the length of the inner strap 406. The inner strap 406 may bea thin strap with the gripping pattern applied to one or both sides ofthe strap 406. The strap 408 can have a similar gripping pattern appliedto the non-stretch segments 412 and 416. In some configurations, thegripping pattern is applied on the portion of the strap facing away fromthe user. In the illustrated configuration, the second strap 408 mayhave a slot in which the inner strap 406 fits in order to retainalignment of the straps and for ease of use of the headgear assembly.For example, the second strap 408 may comprise a passage through whichthe first strap extends. The passage can be formed along a majority of alength of the second strap or the passage can be defined by multipleloops (e.g., similar to belt loops used on clothing).

FIG. 9 illustrates a third embodiment of a layered strap configuration.In this configuration, the layered strap 500 comprises alternatingstretch and non-stretch segments, as in the embodiments discussed above.In the configuration illustrated in FIG. 9, a segment of the strap foldsover. When folded over, gripping portions of the non-stretch segmentscan be aligned, which reduces or eliminates the likelihood of furtherelongation of the headgear. In some configurations, the strap segment isfolded over once the headgear has been stretched to fit over the user'shead and after the user has achieved a desired tension in the interfaceassembly. In some configurations, the strap segment is folded over priorto initiation of pressure-based treatments.

An additional layered strap configuration is shown in FIG. 10. In thisconfiguration, the layered strap 600 has a stretch segment 614 layeredover a non-stretch segment 610. The stretch segment 614 connects twonon-stretch segments 612 (one shown) that overlap with the non-stretchsegment 610 as shown. The non-stretch segments 612 may take the form ofa wrapped segment or a loop or pocket through which or into which thecentral or rear non-stretch segment 610 can be inserted. As discussedabove, each non-stretch segment may have gripping portions that, whenaligned, reduce or eliminate the likelihood of further elongation of theheadgear.

When a force is applied to attempt to elongate headgear having aresistance on demand force profile, such as the non-stretch pathheadgear shown in FIGS. 7A-B and 8-10, there are minimal forces appliedbetween the two strap layers except in the location where the headgearis being held. Accordingly, the grip sections do not interact with eachother and the stretch components are able to elongate withoutsubstantial resistance. When the headgear is released from an elongatedposition, the stretch components relax until the headgear substantiallymatches the user's head circumference. At this point, the non-stretchcomponents and the grip sections on the two strap layers should beoverlapping. The radial force applied by the user's head on the headgearcan cause the grips to interact with each other and lock the length ofthe headgear, limiting further extension or retraction without theapplication of substantial force. The interaction of the grips and theoverlapping stretch/non-stretch sections creates a continuousnon-stretch path through the headgear. This path limits furtherelongation of the headgear when the CPAP pressure is applied. Theheadgear applies an equal and opposite force to the CPAP pressureapplied on the user's face, thus creating a balanced fit. In order toadjust the fit of the mask, the interaction of the gripping sections canbe released or diminished.

Another resistance on demand configuration may be seen in FIGS. 11A-D.With reference to FIG. 11A, in this configuration, a tunnel strapconfiguration 700 has two relatively non-stretch strap segments 704. Insome configurations, the non-stretch strap segments can be formed ofthermoformed compressed material such as Breath-o-Prene. Each strapsegment 704 can be connected to a flexible shuttle 712. Each flexibleshuttle 712 can be connected to the segments 704 and to a low forceelastic member 714. The flexible shuttles 712 and elastic member 714 canbe generally surrounded by a curved head-shaped tunnel 706 with a smoothinner surface made of a soft, non-stretch (at least incircumference/length) material. A number of non-slip pads 708 (twoshown) may be located on the surface of the shuttles 712 closest to theuser. The non-slip pads may be made from silicone or another non-slip ortacky material. One end of each of the shuttles 712 can be aligned withthe ends of the elastic member 714 so that the elastic sits on top ofthe entire length of each shuttle 712. The layered elastic 714 andshuttle 712 configuration can be attached end on end to the relativelynon-stretch strap segments 704. The strap assembly can be housed insidethe tunnel although, in other configurations, the tunnel could have oneopen side.

The flexible shuttles 712 provide the gripping force that establishesthe balanced fit of the headgear. As shown in FIG. 11B, the shuttle 712changes shape depending on the elongation or retraction of the strap andthe amount of force applied. When the strap 704 is pulled, the shuttle712 conforms to the shape of the tunnel 706 and grips, reducing oreliminating the likelihood of further elongation of the headgear. Whenthe strap 704 is released, or is retracting, the shuttle 712 peels awayfrom the surface of the tunnel 706 and breaks the grip, allowing thestrap to retract. FIGS. 11C and D provide further illustration of oneembodiment of the tunnel concept 700 shown in FIGS. 11A and B. FIG. 11Cshows the tunnel strap configuration by itself, while FIG. 11D showsanother embodiment of the tunnel strap configuration attached to a mask.In FIG. 11D, a second strap is shown. The second strap (or set ofstraps) can be positioned below or above the tunnel 706 and/or the strap704. In some configurations, the second strap can be connected to thestrap 704. The second strap can be grabbed by the user and, as such, canbe a handle during donning or doffing of the headgear. In someconfigurations, the second strap helps to orient the headgear duringdonning. In some configurations, the second strap may be positionedgenerally below the maximum occipital point.

An additional resistance on demand configurations is shown in FIGS.12A-12D. In this configuration, another tunnel strap configuration 800has a tunnel 802 that is configured to expose two shuttles 804 to allowsome manual interaction and fit adjustment. By exposing the shuttles804, the user could have additional control over the initial fit of theheadgear. Tabs 806 (one shown) also can be configured to provide aconvenient way for the user to adjust the fit of the headgear. In someconfigurations, pulling the tabs can shorten the strap, for example. Insome configurations, the tabs 806 can be disposed near the ends of thetunnel 802

When a force is applied to elongate headgear having a tunnel mechanismand exhibiting a resistance on demand force profile, such as theheadgear shown in FIGS. 11A-D and FIGS. 12A-12D, the elastic memberelongates freely until a radial force is applied to the mechanism. Untilthe radial force is applied, the axial force applied only needs to begreat enough to overcome the strength of the elastic strap. When theheadgear is released from an elongated position, the elastic strapretracts until the headgear matches the user's head circumference and aradial (e.g., transverse to the strap) force then is applied. At thispoint, the user's head will be applying the radial force to theheadgear. The radial force, combined with the curvature of the tunnel,will cause the non-slip pads on the back of the shuttle to come intocontact with the internal wall of the tunnel, forming a grip and lockingthe length of the headgear, limiting further elongation or retraction.Since the shuttle is preferably a flat piece of plastic, its naturalreaction is to sit at a tangent to the curve of the user's head. Thisresults in the front end of the headgear, where the elastic ispermanently attached, having a predisposition to sit away from theinternal wall of the tunnel, releasing the non-slip pads when there isminimal radial tension applied to the headgear. The friction between thenon-slip pads and the tunnel is typically not enough to prevent theelastic member from retracting in the tunnel.

When a tension force is applied to the headgear by the application ofCPAP pressure, the front of the shuttle is pulled into contact with theinternal wall of the tunnel. The shuttle is pulled into contact with theinternal wall of the tunnel. In this configuration, the non-slip padinteracts with the tunnel, increasing the force required to elongate theheadgear as the tensile forces applied to the headgear increase. Thiseffectively locks the length of the headgear, limiting furtherelongation and retraction unless a force greater than the specifiedapplied force is applied.

FIGS. 13A-13C illustrate yet another embodiment of a resistance ondemand configuration. In this configuration, an air activated lock strap900 provides a balanced fit headgear. One or more air activated lockassemblies 902 can be provided with one on each side of the mask 914.The air activated lock assembly can be connected to, or positionedwithin or along, an elastic strap or the like. In some configurations,the elastic strap can be connected to the mask, the seal of the maskand/or the frame of the mask. In some configurations, the elastic strapcan be connected to the air activated lock. Each air activated lockassembly can have an air activated lock 904 encased by a lock casing906. A supply air tube 908 runs from the mask 914 to each air activatedlock assembly 902. An enlarged view 910 of one of the air activated lockassemblies 902 illustrates that the core strap 912 runs through themiddle of each air activated lock assembly 902. As discussed above, theholding force of the headgear is only required in the presence of CPAPpressure. In this embodiment, the air pressure to maintain the airactivated locks is provided from the air pressure from the mask. Whenthe air activated lock assembly 902 is activated to provide holdingforce for the headgear, such as after a fit has been achieved, air issupplied to each air activated lock 904 from the mask 914. This airpressure causes the air activated lock 904 to expand and grip the corestrap 912, reducing or eliminating the likelihood of further elongationof the headgear strap. Because the air lock assembly 902 is in fluidcommunication with a chamber of the mask, as the pressure increases inthe mask, the pressure increases in the air lock assembly 902. As such,when the forces increase trying to lift the mask from the face, theforces that oppose elongation of the strap also increase. Thisresistance on demand embodiment generally is not applicable to a cannulaset-up. This is because the air locks require the presence of airpressure in order to be activated and, generally, an unsealed cannulasystem is not capable of providing this. An external air pressuresource, that is manually activated, can be provided to the air locks toprovide the holding force required to prevent elongation of the headgeardue to external forces.

FIG. 14 illustrates a second force profile incorporating a balanced fit.In this figure, a high resistance to start movement profile 250 isshown. Headgear configured with this force profile can have a lockingmechanism that gives way at a predetermined force. The load force willremain low as the headgear is elongated to fit over the user's head andretracts for fit until force is again applied to elongate the headgearstrap. As illustrated, the load-elongation curve 252 can have an initialupward slope at low extension that illustrates the high resistance to aninitial elongation of the headgear. After a predetermined force has beenreached, a much lower amount of force is required to further elongatethe headgear. As in the resistance on demand force profile discussedabove, the high resistance to start elongation movement force profilealso includes a balanced fit having two components. First, the balancedfit component 254 provides a high resistance to further elongation overa small range of extension to counteract the blow-off forces of the CPAPpressure. Additional resistance to extension is provided by the reservecomponent 256 that counteracts any external forces, such as hose pull,that may act to elongate or loosen the headgear. In the illustratedconfiguration, the slope of the initial elongation portion of the curveis substantially the same as the slope of the balanced fit component 254of the curve. In some configurations, because the slopes of the initialelongation portion and the balanced fit portion of the curve result fromattempting to overcome the same mechanism in FIG. 14, the slopes will bethe same or substantially the same.

One embodiment of a configuration that incorporates a high resistance tostart elongation profile is shown in FIGS. 15A-B. FIG. 15A illustrates across-section of a roller ball lock mechanism 1000. In thisconfiguration, the locking chamber 1002 includes a roller ball 1004 anda switch 1006. The switch 1006 may be a wedge-shaped member having a topsurface 1012 that lies adjacent to an upper inner surface of the lockingchamber 1002 when the switch is engaged with a core strap 1010. When theswitch 1006 is engaged with the core strap 1010, as shown in FIG. 15A,friction between the roller ball 1004 and the core strap 1010substantially prevents further elongation of the core strap 1010. At apredetermined force, the roller ball 1004 and the switch 1006 changeposition with the switch 1006 pivoting around the pivot point 1008 torelease the core strap 1010 and allow the core strap 1010 to move freelyin either direction, allowing the headgear to elongate or retractfreely. When the direction of movement of the core strap 1010 isreversed, such as when the headgear returns to a smaller circumference,the roller ball 1004 travels to the free side of the locking chamber1002 (to the left in FIG. 15A) and the switch 1006 resets. If the corestrap 1010 is then pulled, the mechanism 1000 again acts as a rollerball lock as described above to resist further elongation of theheadgear.

The locking and release positions of another roller ball lock mechanism1020 are shown in FIG. 15B. In this configuration, the locking chamberincludes a roller ball 1024 and a switch 1026. The switch 1026 may be awedge-shaped member having a top surface 1036 that lies adjacent to anupper inner surface 1038 of the locking chamber 1022. The switch 1026may also include a portion 1040 that is shaped to contain the rollerball 1024 within the locking chamber 1022. In some configurations, theportion 1040 also can be configured to engage with the core strap 1030to reduce or eliminate the likelihood of further elongation of theheadgear when the roller ball lock mechanism 1020 is in a lockedposition. In some configurations, the mechanism 1020 may include amagnet 1032 and a magnetic member 1034. The magnet 1032 may be locatedwithin a housing of the roller ball lock mechanism 1020 while themagnetic member 1034 may be located on one end of the switch 1026,proximal to the surface 1036.

When the switch 1026 is engaged with the core strap 1030, as shown inthe lower illustration of FIG. 15C, friction between the roller ball1004 of the switch 1026 and the core strap 1030 substantially resistsfurther elongation of the core strap 1030. As in the configurationdiscussed with reference to FIG. 15A, at a predetermined force acting toelongate the headgear that overcomes the friction between the rollerball 1004 of the switch 1026 and the core strap 1030, the switch 1026changes position by pivoting around the pivot point 1028 to release thecore strap 1030 and allow the core strap 1030 to move freely. With theswitch in this position, the headgear is substantially free to elongateor retract. When the direction of movement of the core strap 1030 isreversed, such as when the headgear returns to a smaller circumference,the roller ball 1024 travels to the free side of the locking chamber1022 (to the left in FIG. 15B) and the switch 1026 resets. If the corestrap 1030 is then pulled, the mechanism 1020 again acts as a rollerball lock as described above to resist further elongation of theheadgear. The magnet 1032 and the magnetic member 1034 may act to holdand reset the switch 1026.

A second embodiment of a high resistance to start movement configurationis shown in FIGS. 16A and 16B. In this embodiment, self-regulatingwasher friction holds the core strap to reduce or eliminate thelikelihood of further elongation until the friction is overcome and thecore strap is released to elongate or retract with a low load force.FIGS. 16A and 16B include a self-regulating washer mechanism 1100 thatprovides a balanced fit as that concept is discussed above. Theself-regulating washer mechanism 1100 includes an S-shaped frictionmember 1104 having a bendable curve 1110 and a self-regulating washer1106 adjacent to the bendable curve 1110 portion of the S-shaped member1104. The friction member 1104 and the curve 1110 can be positionedwithin a housing 1111 and a stretch component 1113 can be secured to thehousing 1111, for example but without limitation. A core strap 1108 ofthe headgear passes through an orifice in the S-shaped member 1104 andalso through the washer 1106. The core strap 1108 can pass through oralongside at least a portion of the stretch component 1113.

When the washer 1106 and S-shaped member 1104 are at an angle α to alongitudinal axis of the core strap 1108, designated by 1112 in FIG. 16,the core strap 1108 resists elongation due to frictional forces betweenthe washer 1106 and the core strap 1108 and the S-shaped member 1104 andthe core strap 1108. These frictional forces may be overcome withadditional load force applied to the core strap 1108. When sufficientforce is applied to the S-shaped member, the orifices of the S-shapedmember 1104 and the washer 1106 become better aligned due to flexure ofthe S-shaped member. With flexure, the self-regulating washer mechanism1100 takes the shape as shown in the lower panel of FIG. 16. In thisconfiguration, the bendable curve 1110 and the washer 1106 are at anangle β to the longitudinal axis, designated by 1114 in FIG. 16. Theangle 1114 is closer to ninety degrees than the angle 1112, allowing thecore strap 1108 to more easily pass through the openings in the S-shapedmember 1104 and the washer 1106. In this configuration, the frictionalforces exerted on the core strap 1108 are less, allowing the core strap1108 to elongate and retract with less required load force. When thedirection of pull on the core strap 1108 is reversed, the bendablemember 1110 of the S-shaped frictional member 1104 and the washer 1106return to an orientation similar to that in the top panel of FIGS. 16Aand 16B. As discussed above, this configuration limits elongation of thecore strap 1108 due to frictional forces on the core strap 1108 until asufficiently high load is applied, which load is greater than thattypically encountered during normal treatment use of a CPAP device.

FIG. 17 illustrates a third force profile incorporating a balanced fitfeature. In this figure, a repeated high resistance to elongation loadprofile 270 is shown. Headgear configured with this force profile has alocking mechanism that gives way at a predetermined force beforeresetting. This sequence of release and reset repeats throughout theextension of the headgear. As shown in FIG. 17, the load curve 272 iscomposed of a series of repeating high load force peaks as the headgearis extended. The load curve 272 requires less force to retract, as shownby the lower portion of the curve 272. As with the force profilesdiscussed above, a balanced fit component 274 and a reserve component276 respectively compensate for the blow-off forces and prevent furtherelongation of the headgear due to external forces such as hose pull.Moreover, as illustrated, the balanced fit component 274 can have aload-extension slope that approximates the load-extension slope of theincreasing load portion of the load curve 272.

A ratchet mechanism 1200 that provides a repeated high resistance toelongation is shown in FIGS. 18A-B. The illustrated ratchet mechanism1200 includes a housing 1204 having an interior cavity 1206 housing aspring-loaded clip 1208. The clip 1208 is configured to interact withthe serrated edge of a non-stretch core strap 1212 that runs through thehousing 1204. When the core strap 1212 is pulled or extended, the clip1208 engages with the serrated edge of the core strap 1212 to resistfurther elongation. The grip of the clip 1208 on the strap 1212 isovercome when the clip 1208 flexes away, releasing its grip on a singletooth. The spring loaded clip 1208 is then ready to engage with the nexttooth of the serrated core strap 1212. Again, upon application ofsufficient load force, the clip 1208 releases the next serration of thecore strap 1212 and catches on the following serration. In this way, arepeated high resistance to elongation force profile such as the oneshown in FIG. 17 is achieved. The illustrated clip 1208 is perpendicularto the core strap 1212 during extension of the serrated core strap 1212and can be angled during retraction of the core strap 1212.

The core strap 1212 can be housed inside a stretch sheath (not shown)and can extend beyond both ends of the sheath into a plastic tube wherethe loose ends are housed. The stretch sheath provides the retractionforce to return the headgear to the size of the user's head. The Young'smodulus of the stretch sheath preferably is tuned so that the sheathapplies a force to the user's head that is less than or equal to theminimum possible blow-off force such that the sheath provides theinitial balancing force. For higher blow-off forces, the non-stretchcomponents may provide the additional balancing forces.

The core strap 1212 preferably has stoppers on the ends to reduce oreliminate the likelihood of the ends of the strap 1212 being pulled outof the housing tube. The core strap 1212 forms a closed loop with thehousing. The tubular housing can clip into the mask frame. Clip housings(not shown) can connect the stretch sheath and housing together.

When an extension force is applied to the headgear, the core strap 1212pulls the clip 1208 flush against the square internal wall of thehousing 1204. This causes the clip 1208 to further engage with the teethon the core strap 1212. The engagement is overcome when the clip 1208flexes away, releasing its grip on a single tooth, ready to engage withthe next tooth. The force required to overcome each tooth on the corestrap and elongate the headgear is greater than or equal to thespecified applied force.

When the headgear is released from an elongated position, the clip 1208rotates in its housing 1204, becoming flush with the angled wall of thehousing 1204. This allows the clip 1208 to disengage the teeth of thecore strap 1212, which in turn allows the headgear to retract freely.

Initially, the CPAP pressure is balanced by the low force applied by theelastic component to the user's head. As the force applied by the CPAPpressure increases, the non-stretch core strap 1212 will provideadditional resistance to elongation, pushing the spring clip 1208against the perpendicular housing wall and engaging the teeth, thusproviding the remainder of the balancing force. As the force applied bythe CPAP pressure preferably does not exceed the specified yield forceto overcome the teeth on the core strap 1212, the length of the headgearwill remain substantially constant unless modified by the user.

Retraction of the core strap 1212 is shown in FIG. 18B. In this figure,the core strap 1212 is retracted through the housing 1204, causing theclip 1208 to rotate within the housing 1204 thus allowing the clip 1208to disengage from the teeth of the core strap 1212. The strap 1212 canretract with very little resistance in this configuration.

FIGS. 19A and B illustrate the ratchet mechanism integrated into oneembodiment of a strap design 1218. An elastic sleeve 1220 surrounds theratchet mechanism to automatically retract the headgear.

A fourth force profile incorporating a balanced fit is shown in FIG. 20.In this figure, a large hysteresis load profile 290 is shown. Headgearconfigured with this force profile has a high load force resistance toelongation or extension. With reference to FIG. 20, the high build-up offorce is shown in the extension section 292 of the load curve. Duringthis extension phase of the headgear, the extension force may be betweenabout 7 and 8 N as determined by the sum of the blow-off force and anestimated 3 N hose pull force. When the headgear retracts, as shown inthe retraction section 294 of the load curve, the returning force ispreferably no greater than about 2.5 N. This returning force is theforce exerted on a user's face primarily by the elastic component of theheadgear.

A balanced fit of the headgear may comprise two components, as discussedabove: a balanced fit component and a reserve component. The balancedfit component 296 of the load curve shown in FIG. 20 compensates for theblow-off force applied by the CPAP pressure. The reserve component 298of the load curve may cover a range of load forces extending up to theload force during the large hysteresis section of the extension curve292. In some embodiments, the extension during the balanced fit phase isno greater than about 10 mm. As shown, in some configurations, thebalanced fit component 296 follows a slope similar to or the same as theinitial elongation slope. In some configurations, the balanced fitcomponent 296 has a lower slope than the slope of the retraction section294. Other configurations are possible.

FIGS. 21A and B illustrate a cross section of one embodiment of aheadgear mechanism that incorporates the large hysteresis load profilediscussed above. In this embodiment, a washer concept headgear mechanism1300 includes a housing 1304 having an internal cavity 1306. Theinternal cavity 1306 is configured to have a free movement surface 1310that is substantially vertical and orthogonal to a longitudinal axisdefined by a core strap 1316. The internal cavity 1306 is alsoconfigured to have a locking surface 1312 that is angled with respect tothe longitudinal axis defined by the core strap 1316. A washer 1308 islocated within the internal cavity 1306. An orifice through both thehousing 1304 and the washer 1308 allow a non-stretch core strap 1316 tobe threaded through the orifices. The housing 1304 forms the ends of atube that houses the ends of the non-stretch core strap 1316. In someconfigurations, the tube is generally elastic. This tube can make theheadgear into a closed loop and can clip into the mask frame (notshown).

With reference to FIG. 21A, free movement of the core strap 1316 isillustrated. When the washer 1308 is aligned with the free movementsurface 1310 of the housing 1304, there is little to no friction betweenthe washer 1308 and housing 1304 and the core strap 1316. Therefore, inthis configuration, the core strap 1316 has a substantially straightpath through the washer 1308 and the housing 1304 and is substantiallyfree to move in the free movement direction indicated by arrow 1318.

With reference now to FIG. 21B, high friction resistance to movement ofthe core strap 1316 is illustrated. When the core strap 1316 is pulledin the opposite direction of the free movement direction, indicated byarrow 1320, the washer 1308 is forced to tip over and rest adjacent tothe angled locking surface 1312 of the housing 1304. This orientation ofthe washer 1308 within the housing 1304 creates an angled path for thecore strap 1316. This angled path increases the friction between thewasher 1308 and the core strap 1316. The increased friction limitsmovement of the core strap 1316, which resists elongation of theheadgear. FIGS. 22A-22D illustrate one embodiment of a washer conceptheadgear mechanism incorporated within a headgear assembly. As shown inFIGS. 22A-22D, each headgear assembly can include two washer mechanismson a non-stretch core strap. The middle section of the core strap can behoused inside a stretch sheath. The core string preferably has stopperson the ends to reduce or eliminate the likelihood of the core stringbeing pulled out of the housing tube. The stretch sheath is desirablyconnected to the housing tube at both ends. FIG. 22A also illustrates afree movement configuration at 1330. FIG. 22B at 1332 illustrates a highfriction movement configuration.

Three additional embodiments of a washer concept that provides highfriction resistance to movement of a core strap are shown in FIGS.23A-23C. As illustrated in each concept 1340, 1350, and 1360, the washershape may change from a flat washer 1342 to an angled washer 1352 orangled washer 1362 depending on the construction of the housing. In eachcase, alignment of the washer 1342, 1352, or 1362 along the freemovement surface 1344, 1354, or 1364 of the housing will allow the corestrap 1348, 1358, or 1368 to move substantially freely through thewasher and the housing. However, when the washer 1342, 1352, or 1362rotates within the housing to align with the locking surface 1346, 1356,or 1366 of the housing, the core strap is bent, creating an angled, highfriction path of movement that limits further elongation of theheadgear.

A further embodiment of a washer concept mechanism is illustrated inFIGS. 24A-24E. In this embodiment, the mechanism 1370 includes a washer1372 disposed within a housing 1374. A rotatable member 1376 is alsodisposed within the housing 1374. As discussed above with respect to theother washer embodiments, movement of the washer 1372 from one end ofthe housing to the other influences whether a free movement or highfriction movement condition exists. The rotatable member 1376 within thewasher mechanism 1370 provides an additional benefit such that themechanism 1370 is less influenced by a change in pulling angle of thecore strap 1378.

In any of the above discussed embodiments, the housing may bemanufactured in one or more pieces. The housing and the washer may bemanufactured of the same or different materials. In some configurations,the housing and/or the washer can be formed of a generally rigidmaterial. In some configurations, the housing and/or the washer can beformed of a rigid plastic. In some configurations, the housing and/orthe washer can be formed of a polycarbonate, a polypropylene, an acetylor a nylon material. In some configurations, the housing and/or thewasher may be formed of a metal.

When headgear having any of the washer mechanisms discussed above withreference to FIGS. 21A-B, 22, 23, and 24 are extended, the small amountof friction between the washer and the core strap causes the washer tobe pulled towards the angled end wall of the housing. This results inthe washer sitting on an angle inside the housing, creating a crookedpath for the core strap to pass through. This crooked path creates atension force in the core strap and increases the resistance to movementbetween the core strap and the washer mechanism. The resistance is suchthat a force greater than the specified yield force is required toelongate the headgear.

When there are no tension forces on the headgear including a washermechanism, the washer returns to its neutral position adjacent to theperpendicular end wall. In this position, the washer imposes minimalfrictional forces on the core strap. When the headgear is released, thecore strap can be drawn freely through the housing and the washer. Theelastic sheath provides the retraction force required to shorten theheadgear.

The elastic sheath also allows for elongation of the headgear when aforce greater than the specified yield force is applied. The Young'smodulus of the elastic sheath is preferably tuned so that the sheath canonly apply a force to the user's head that is less than or equal to theminimum possible blow-off force. Thus, for these configurations, theelastic provides the initial balancing force for low CPAP pressures.

Initially, the CPAP pressure will be balanced by the low level of forceapplied by the elastic component to the user's head. As the forceapplied by the CPAP pressure increases, the non-stretch core strap, inconjunction with the washer mechanism, will limit further elongation.The headgear's natural reaction to an increase in CPAP pressure is toelongate to accommodate the pressure increase; however, this will resultin the washer being pushed toward the angled end of the housing, lockingthe non-stretch core strap in place due to the increased friction. Oncethe movement of the core strap is restricted, the core strap willprovide the remainder of the balancing force. As the force applied bythe CPAP pressure will typically not exceed the specified yield force toovercome the resistance of the washer on the core strap, the length ofthe headgear will remain substantially constant, unless modified by theuser.

Another embodiment of a large hysteresis mechanism is shown in FIGS.25A-C. A cross-section of a C-ring mechanism 1400 is shown in FIG. 25A.The mechanism 1400 includes a rigid tubular housing 1404 that may beformed contiguously with a strap member 1410 or may be a separate piece.The housing 1404 includes an orifice through which a non-stretch sectionof a core strap 1408 may pass. The housing 1404 also contains the looseends of the core strap (not shown). Within the housing is a resilientwasher with a C-shaped cross-section 1406. The washer 1406 is orientedsuch that the opening of the washer 1406 is oriented toward the mask.The flexible C-shaped washer 1406 may be made of silicon or rubber. Withreference to FIG. 25A, the opening defined through the C-shaped member1406 is oriented in a direction substantially similar to thelongitudinal axis of the core strap 1408. At least one leg of eachC-shaped member 1406 is adjacent to the core strap 1408. The C-shapedsection of the washer 1406 drags over the surface of the non-stretchsection of the core strap 1408 that passes through the housing 1404. Thehousing 1404 and the washer 1406 are configured such that the washer1406 exerts significant friction when the core strap 1408 is moved inone direction and movement of the core strap 1408 in the other directionis substantially free, as will be discussed in greater detail below.

With reference now to FIGS. 25B and C, free movement and high frictionmovement of the core strap 1408 are shown. Depending on the direction ofmovement, the washer 1406 reacts differently. When the core strap 1408is moving the in free movement direction 1414, the center of the washer1406 tends to “unroll,” as shown in FIG. 25B. When the center of thewasher 1406 unrolls, friction on the core strap 1408 is reduced. Whenthe core strap 1408 is moving in the other direction, a high frictionmovement direction 1416, as shown in FIG. 25C, the center of the washer1406 in contact with the core strap 1408 is crunched up or compressed.This deformation increases the friction on the core strap 1408,increasing the force required to elongate the headgear. FIGS. 26A-26Cillustrate two views of one embodiment of a headgear assembly having aC-ring mechanism as discussed above. The middle section of the corestrap 1408 is housed inside a stretch sheath. The stretch sheath can beconnected to the housing 1404 at both ends. The stretch sheath providesthe retraction force to return the headgear to the size of the user'shead. The Young's modulus of the stretch sheath can be tuned so that thesheath can apply a force to the user's head that is less than or equalto the minimum possible blow-off force. This means that the stretchsheath provides the initial balancing force. In cannula systems, theYoung's modulus can be tuned to be the lowest possible or practicablerequired to hold the cannula to a user's head, in order to maximizecomfort. For high blow-off forces (or external forces in a cannulasystem), the non-stretch components will provide the additionalbalancing forces. The core strap 1408 preferably has stoppers on theends to reduce or eliminate the likelihood of the ends being pulled outof the housing 1404. By containing the ends of the core strap 1408, theheadgear forms a closed loop. The housing 1404 preferably clips into themask frame to connect the headgear to the mask.

In the embodiments shown in FIGS. 25A-C, when an extension force isapplied to the headgear, the core strap 1408 pulls the round section ofthe washer 1406 against the internal wall of the housing 1404. Thiscauses the washer 1406 to crush and increases the friction on the corestrap 1408. The friction provided by the washer 1406 is such that theforce required to elongate the headgear is greater than the specifiedyield force. When the headgear is released from an elongated position,the washer 1406 returns to its natural shape, allowing the core strap1408 to pass through the housing 1404 and through the washer 1406 withsubstantially lower resistance. When the open side of the washer 1406 ispulled against the wall of the housing 1404, it does not crumple ordeform and the friction on the core strap 1408 remains low.

Initially, the CPAP pressure will be balanced by the low level of forceapplied by the elastic or stretch component to the user's head. As theforce applied by the CPAP pressure increases, the non-stretch core strap1408 acts to restrict further elongation. The natural reaction of theheadgear is to elongate to accommodate the increased CPAP pressure;however, this will result in the round side of the washer 1406 beingpushed against the wall of the housing 1404, increasing friction and“locking” the non-stretch core strap 1408 in place. Once the movement ofthe core strap 1408 is restricted, it will provide the remainder of thebalancing force. As the force applied by the CPAP pressure typicallydoes not exceed the specified yield force to overcome the friction ofthe washer 1406 on the core strap 1408, the length of the headgear willremain substantially constant unless modified by the user.

Another embodiment of a large hysteresis mechanism is illustrated inFIGS. 27A-27D. In FIG. 27A, an alternative washer mechanism 1500includes a housing 1504 that incorporates a crushable core member 1506.The crushable core member 1506 may be configured in a cone shape suchthat the cone can crush or deform to increase friction on the core strap1508. When the core strap 1508 moves in the free movement direction,indicated by arrow 1510, friction on the core strap 1508 is minimal andthe crushable core member 1506 does not substantially resist freemovement of the core strap 1508, as shown in FIG. 27B. When the corestrap 1508 moves in the high friction movement direction, indicated byarrow 1512, the crushable core member 1506 is deformed or “crunches up”to the left, as shown in FIG. 27C.

With continued reference to FIG. 27A, graph 1520 indicates that as theresistance increases due to the deformation of the crushable core member1506, the resistance to movement of the core strap 1508 steeplyincreases. The resistance to movement remains high for furtherelongation of the core strap 1508, corresponding to a large hysteresisforce profile such as the one described with reference to FIG. 20.

Yet another embodiment of a large hysteresis mechanism is illustrated inFIGS. 28A and 28B. In FIG. 28A, a roller ball lock mechanism 1600includes a rigid tubular housing 1604 having an interior chamber 1608.The interior chamber 1608 is ramped to be larger at one end than theother. The interior ramped chamber 1608 houses a roller ball 1606. Theroller ball 1606 is encased between the wall of the interior rampedchamber 1608 and a non-stretch core strap 1610. The housing 1604 furtherincludes an orifice such that the core strap 1610 may pass through thehousing and further contains the loose ends of the core strap 1610,forming a closed loop. The core strap 1610 preferably has stoppers onthe ends to prevent the ends from being pulled out of the housing 1604.The housing 1604 can then clip into the mask frame. In thisconfiguration, when the roller ball 1606 is at one end of the interiorcavity 1608, the roller ball 1606 presses against the core strap 1610,increasing friction and the load force required to further extend thecore strap 1610. With continued reference to FIG. 28A, when the corestrap 1608 is pulled in the direction indicated by arrow 1612, theroller ball 1606 is driven into the smaller end of the interior cavity1608. Due to the ramped shaped of the interior cavity 1608, when thecore strap 1608 is moved in the opposite direction, the roller ball 1606is driven to the “high ceiling” end of the interior cavity 1608 wherethere is greater room for the roller ball 1606. Therefore, the rollerball 1606 has minimal interference with the core strap 1608, therebyreducing the friction exerted by the ball. One example of this rollerball lock mechanism incorporated within a headgear assembly is shown inFIG. 28B. The middle section of the core strap 1610 is housed within astretch sheath 1612. The stretch sheath 1612 can be connected to thehousing 1604 at both ends. The stretch sheath 1612 provides theretraction force to return the headgear to the size of the user's head.The Young's modulus of the stretch sheath 1612 is preferably tuned sothat the sheath 1612 can only apply a force to the user's head that isless than or equal to the minimum possible blow-off force. This meansthat the stretch sheath 1612 provides the initial balancing force. Incannula systems, the Young's modulus can be tuned to be the lowestpossible or practicable required to hold the cannula to a user's head,in order to maximize comfort. For higher blow-off forces, thenon-stretch components will provide the additional balancing forces.

When an extension force is applied to headgear having the roller ballmechanism described above with reference to FIGS. 28A-C, the core strap1610 pulls the roller ball 1606 towards the narrow end of the rampedchamber of the housing 1604. This subsequently drives the roller ball1606 into the core strap 1610 and increases the friction on the corestrap 1610. The increased friction is such that the force required toelongate the headgear is greater than the specified yield force.

When the headgear is released from an elongated position, the rollerball 1606 is driven back towards the wider end of the ramped chamber ofthe housing 1604, thus reducing the friction on the core strap 1610 andallowing the core strap 1610 to pass through the chamber withsubstantially lower resistance.

Initially, CPAP pressure will be balanced by the low level of forceapplied by the stretch sheath component 1612 to the user's head. As theforce applied by the CPAP pressure increases, the non-stretch core strap1610 will act to resist further elongation. The headgear will naturallywant to elongate to accommodate the CPAP pressure; however, this willresult in the roller ball 1606 being pushed towards the narrow end ofthe ramped chamber 1608, “locking” the core strap 1610 in place. Oncethe movement of the core strap 1610 is resisted, it will provide theremainder of the balancing force. As the force applied by the CPAPpressure typically does not exceed the specified yield force to overcomethe friction of the roller ball 1606 on the core strap 1610, the lengthof the headgear will remain substantially constant unless modified bythe user.

A second roller ball lock mechanism 1620 having a large hysteresis forceprofile is illustrated in FIG. 28C. In this figure, the mechanism 1620includes a housing 1624 having an interior chamber 1628 that includes aseparate wedge or switch member 1632. The wedge member 1632 acts as ahinged release switch that is encased between the roller ball 1626 andthe chamber 1628. In this embodiment, the wedge member 1632 is includedto improve the quick release of the roller ball 1626 from the core strap1630. The wedge member 1632 has an angled surface that creates a rampedchamber when engaged and a rectangular chamber when released. The middlesection of the core strap 1630 is housed within a stretch sheath similarto the sheath 1612 shown in FIG. 28B. The stretch sheath can beconnected to the housing 1624 at both ends. The stretch sheath providesthe retraction force to return the headgear to the size of the user'shead. The Young's modulus of the stretch sheath is preferably tuned sothat the sheath can only apply a force to the user's head that is lessthan or equal to the minimum possible blow-off force. This means thatthe stretch sheath provides the initial balancing force. In cannulasystems, the Young's modulus can be tuned to be the lowest possible orpracticable required to hold the cannula to a user's head, in order tomaximize comfort. For higher blow-off forces, the non-stretch componentswill provide the additional balancing forces.

Upon reversal of direction to a free movement direction, as indicated bythe arrow 1634, the wedge 1632 and the roller ball 1626 move together asmall distance before the wedge 1632 falls away within the cavity 1628,instantly releasing the grip between the core strap 1630 and the rollerball 1626. The core strap 1630 is then allowed to move freely.

The switch 1632 is naturally in an engaged position, creating a rampedchamber. When an extension force is applied to the headgear, the corestrap 1630 pulls the roller ball 1626 towards the end of the chamber1628 that is made narrow by the switch 1632. As the ball 1626 is driveninto the switch 1632, the compression force increases until the rollerball 1626 is directly over the axis of rotation of the switch 1632, atwhich point the switch 1632 is released. The release of the switch 1632creates a rectangular chamber 1628 and reduces the resistance betweenthe switch 1632, ball 1626, and core strap 1630, allowing the ball 1626to move within the chamber 1628 and the headgear to be extended easilywith only the force required to overcome the elastic stretch sheath andsome frictional forces between the mechanism components.

When the switch 1632 has been released and the ball 1626 has rolled tothe extension end of the chamber 1628, the core strap 1630 can movethrough the mechanism 1620 with minimal resistance in both directions.Resetting the switch 1632 is done after the core strap 1630 reverses itsdirection of travel and returns the ball 1626 to the other (retraction)end of the chamber 1628. Once the ball 1626 has been rolled back pastthe switch 1632 rotation axis, the switch 1632 is reset and the chamber1628 becomes ramped again.

When the headgear is released from an elongated position and allowed toretract, the roller ball 1626 is driven back towards the extension, ormore open, side of the chamber 1628. The change in position of theroller ball 1626 re-engages the switch 1632 but also maintains the lowerresistance level between the components, allowing the core strap 1630 topass through the chamber 1628 with little resistance.

Initially, the CPAP pressure will be balanced by the low level of forceapplied by the elastic sheath component to the user's head. As the forceapplied by the CPAP pressure increases, the non-stretch core strap 1630will provide additional resistance to elongation. The headgear's naturalreaction will be to elongate to accommodate the CPAP pressure; however,this will result in the roller ball 1626 being pushed towards the angledswitch 1632 surface which will cause an increase in friction between theball 1626, core strap 1630, and the switch 1632. The force applied bythe air pressure will preferably not be enough to overcome the frictionand cause the switch 1632 to release, thus further elongation of theheadgear will be limited. The switch force is preferably about equal tothe specified yield force.

FIGS. 29A-29C illustrate an alternative embodiment to the roller ballmechanism for large hysteresis. A collet mechanism 1700 includes a twopart housing 1704, 1706 that is conical at one end. The housing members1704, 1706 for the ends of a rigid tubular housing that contains theloose ends of a non-stretch core strap 1710. The housing contains acollet member 1708 that forms a collar around the core strap 1710. Thecollet member 1708 preferably has the shape of a truncated cone and, asin the illustrated embodiment, may have one or more kerf cuts along itslength to allow the collet member 1708 to expand and contract. Thecollet member 1708 exerts a strong clamping force on the non-stretchcore strap 1710 when the collet member 1708 is pulled in the directionindicated by arrow 1712 that is, into the conical chamber formed in thehousing. Similar to the roller ball mechanisms discussed above, the corestrap 1710 experiences high frictional forces when the collet member1708 is pulled into the conical chamber of the housing. The core strap1710 is substantially free to move when pulled in the oppositedirection.

The middle section of the core strap 1710 is housed within a stretchsheath that is connected to the housing at both ends, as described abovewith reference to other embodiments. The non-stretch core strap 1710preferably has stoppers on the ends to reduce or eliminate thelikelihood of the loose ends being pulled out of the housing, forming aclosed loop headgear assembly. The housing tube can clip into a maskframe.

When an extension force is applied to the headgear, the core strap 1710pulls the collet member 1708 into the conical end of the housing. Thiscauses the collet member 1708 to be compressed onto the core strap 1710,increasing the friction between the two components. The frictionprovided by the compressed collet member 1708 is such that the forcerequired to elongate the headgear is greater than the specified appliedforce.

When the headgear is released from an elongated position, the colletmember 1708 returns to its neutral position which allows the core strap1710 to pass through it more freely. The elastic sheath provides theretraction force to return the headgear to the size of the user's head.The Young's modulus of the elastic sheath may be tuned so that thesheath can only apply a force to the user's head that is less than orequal to the minimum possible blow-off force. In this configuration, theelastic provides the initial balancing force. For higher blow-offforces, the non-stretch components will provide the additional balancingforces.

Initially, the CPAP pressure will be balanced by the low level of forceapplied by the elastic component to the user's head. As the forceapplied by the CPAP pressure increases, the non-stretch core strap 1710will restrict further elongation. The headgear's natural reaction is toelongate to accommodate the CPAP pressure; however this will result inthe collet member 1708 being pushed towards the conical end of thehousing and thus the non-stretch core strap 1710 will be locked inplace. Once the movement of the core strap 1710 is restricted it willprovide the remainder of the balancing force. As the force applied bythe CPAP pressure preferably does not exceed the specified yield forceto overcome the friction of the collet member 1708 on the core strap1710, the length of the headgear will remain constant unless modified bythe user.

For headgear that provides a large hysteresis force extension profile incombination with the mask, the force required to extend the headgear forfitting is preferably not much higher than the specified yield force toallow easy recognition of the adjustment function by the user. A veryhigh extension force might cause user confusion as this large requiredforce may appear unnatural and the user might fear breaking a componentof the headgear.

The headgear also preferably allows the fit to be adjusted to the user'spreference. FIG. 30 illustrates a force profile for a large hysteresismechanism headgear that includes a section that allows the user tochoose how they want the seal of the mask to fit. This force profilealso takes into account differing facial geometries between users. Theuser will be able to push the mask onto their face to create a largercontact area and tighter fit with the seal, due to further retraction ofthe strap. This will increase the force applied by the headgear but willnot exceed the force required to overcome the friction mechanism, suchas those described above, and elongate the headgear. For users whoprefer a loose fit, the non-stretch or low-stretch component of theheadgear will enable the mask to be held in place with the minimum forcerequired to counter the blow-off force while still maintaining a sealwith the user's face, or counter the weight of and hold a cannula inplace.

Force profiles at various pressures are shown in FIGS. 31A and B. FIG.31B illustrates the force profile of the Pilairo elastic strap headgear.It is clearly visible that the force is nearly constant and is hardlyinfluenced by CPAP pressure. This figure also shows a wide spreadbetween test subjects which is a result of the different head sizes ofeach test user.

In contrast, the graph shown in FIG. 31A is generated using aone-way-friction head strap. In this example, a tunnel concept headgearis used, but our other concepts such as those discussed above would havegenerated similar results. This figure illustrates the advantage of abalanced fit. At low pressures, the headgear produces considerably lowerforces on the user's head as compared to the Pilairo elastic strapheadgear. FIG. 31A also shows less spread in measurements of differentusers. The spread comes from the way the seal is created, as some peopleneed or prefer more engagement than others.

FIG. 31C illustrates the difference between the average of each of thefirst two graphs shown in FIGS. 31A and B. In this graph, it is easy tosee the large force difference at the lower end of CPAP pressure scale.Headgear that includes one of the mechanisms discussed above can improveuser comfort. This is especially true in combination with an intelligentsupply of CPAP, such as a pressure ramping or varying pressuretechnology.

Note that FIG. 31C reflects average values; however, the balanced fitmechanism is designed to optimize the effect for each individual user.

FIG. 32 illustrates an adjustment mechanism 1800 having variabledirectional properties, which can be utilized in a self-fit interfaceassembly. The illustrated adjustment mechanism 1800 provides directionallocking functionality and, thus, can be referred to as a directionallocking mechanism or, simply, a directional lock. The directional lock1800 allows relative movement between two components in a firstdirection at a first level of resistance and provides a second,preferably higher level of resistance in response to relative movement(or attempted relative movement) in a second direction, which inhibitsor prevents relative movement in the second direction in response to atleast some loading conditions. In some configurations, the directionallock 1800 prevents relative movement in the second direction in responseto normal operational forces, such as one or more of CPAP-producedblow-off force and external force (e.g., hose pull force). Thedirectional lock 1800 can also prevent relative movement in the seconddirection in response to additional forces above the expected or normalblow-off force and/or hose pull force to provide a reserve, as describedpreviously. Thus, the directional lock 1800 can be configured to providea locking function only in response to normal operational forces (plus areserve, if desired) and can allow relative movement between the twocomponents in response to forces of a magnitude above the normaloperational forces (and reserve, if desired) to permit, for example,extension of the headgear portion of the interface assembly during theapplication phase of the fitment process. Thus, a headgear arrangementincorporating such a directional lock 1800 can “transform” from stretchbehavior to non-stretch behavior or from elastic elongation typebehavior to non-elongating type behavior. As used herein, elongation isnot necessarily limited to referring to movement in an extensiondirection, but can refer generally to stretch or elastic behavior incontrast to non-stretch or non-elastic/inelastic behavior. Thedirectional lock 1800 (and other directional locks described herein) canalso be referred to as transformational locks that providetransformational locking behavior.

The directional lock 1800 of FIG. 32 is similar in general operationalprinciples to the arrangements of FIGS. 16 and 21 in that a floating ormovable lock component or member 1802 (e.g., lock washer or lock plate)is movable between a first, lower resistance or release position and asecond, higher resistance or lock position. Features or details notdescribed with respect to the directional lock 1800 of FIG. 32 can bethe same as or similar to corresponding features of the arrangements ofFIGS. 16 and 21, or can be of another suitable configuration. Theillustrated directional lock 1800 includes a core member 1804, such as acore strap or core wire/cord, that passes through an opening of the lockwasher 1802. The lock washer 1802 is supported within an enclosure or ahousing 1806 for movement between the first position and the secondposition. Preferably, the housing 1806 includes a first wall 1810 havinga first stop surface 1812 that supports the lock washer 1802 in thefirst position, which preferably is the lower resistance or releaseposition. The housing 1806 preferably also includes a second wall 1814having a second stop surface 1816 that supports the lock washer 1802 inthe second position, which preferably is the higher resistance or lockposition. Preferably, the stop surfaces 1812, 1816 are sized, shaped orpositioned to support the lock washer 1802 in the desired position.Thus, the stop surfaces 1812, 1816 can be continuous surfaces thatcontact an entirety or a substantially entirety of the cooperatingsurface of the lock washer 1802, as illustrated. Alternatively, the stopsurfaces 1812, 1816 can be intermittent or discontinuous surfaces, orcan contact one or more portions of the lock washer 1802, such as upperand lower end portions of the lock washer 1802, for example.

Preferably, the lock washer 1802 is positioned generally perpendicularto a longitudinal axis of a portion of the core member 1804 positionedwithin the lock cavity of the housing 1806 in the first, lowerresistance or release position such that the opening or hole of thewasher 1802 is positioned generally parallel to or aligned with the coremember 1804. Preferably, the lock washer 1802 is positioned at anoblique angle relative to the longitudinal axis of a portion of the coremember 1804 positioned within the lock cavity of the housing 1806 in thesecond, higher resistance or lock position such that the opening or holeof the washer 1802 is positioned at an oblique angle to the core member1804. Thus, in some configurations, the first stop surface 1812 can begenerally perpendicular to a portion of the core member 1804 positionedwithin the lock cavity of the housing 1806 (and/or the openings in thehousing 1806 through which the core member 1804 passes) and the secondstop surface 1816 can be positioned at an oblique angle Θ relative to aportion of the core member 1804 positioned within the lock cavity of thehousing 1806 (and/or the openings in the housing 1806 through which thecore member 1804 passes). As discussed below, the angle of the secondstop surface 1816 or the lock washer 1802 when contacting the secondstop surface 1816 can be selected to achieve a desired lock or yieldforce or magnitude of resistance when the lock washer 1802 is in thelock position.

The housing 1806 can be coupled to one component of the interfaceassembly and the core member 1804 can be coupled to another component ofthe interface assembly such that relative movement between the housing1806 and the core member 1804 occurs during extension or retraction ofthe headgear portion of the interface assembly during the fitmentprocess. Frictional engagement between the core member 1804 and the lockwasher 1802 moves the lock washer 1802 between the first and secondpositions depending on the direction of relative movement between thecore member 1804 and the housing 1806 or retains the lock washer 1802 inone of the first and second positions depending on the direction offorces applied to the core member 1804 and/or housing 1806. Accordingly,with such an arrangement, the directional lock 1800 can be utilized toprovide variable directional resistance characteristics in a self-fitinterface assembly, similar to other embodiments described herein.

FIG. 33 illustrates a directional lock 1820 that is similar to thedirectional lock 1800. Accordingly, the same reference numbers orcharacters are used to indicate the same or corresponding components orfeatures. The directional lock 1820 incorporates a release mechanism1822 that releases the core member 1804 or reduces the resistance tomovement of the core member 1804 upon a certain force being applied tothe core member 1804 to limit the lock force of the directional lock1820. That is, the release mechanism 1822 permits the lock washer 1802to move from the lock position to a secondary lock position that iscloser to perpendicular to the core member 1804 or closer to the releaseposition, but in response to a force applied in a direction tending tomove the lock washer 1802 to the lock position. Thus, the releasemechanism 1822 influences to some extent the lock or yield force of thelock function of the directional lock 1802.

In the illustrated arrangement, the release mechanism 1822 comprises abiasing member or arrangement, such as a spring 1824. The spring 1824supports the lock washer 1802 (along with a portion of the secondsurface 1816 of the housing 1806) in the lock position to inhibit orprevent relative movement between the core member 1804 and the housing1806 in response to expected or normal operational forces. Preferably,the characteristics of the spring (e.g., spring rate, preload, etc.) areselected such that the lock washer 1802 can move against a biasing forceof the spring 1824 toward or to the secondary lock position in responseto a desired force magnitude, which can be greater than the expected ornormal operational force (including one or more of blow-off forces, hosepull forces and a reserve). In the illustrated arrangement, the lockwasher 1802 contacts the second surface 1816 of the housing 1806substantially opposite of the spring 1824 in the lock position andpivots about that pivot surface or pivot point 1826 when moving towardthe secondary lock position. The distance between the pivot point 1826and the location of the spring 1824 (or effective location of any otherbiasing arrangement) can be referred to as the lever length of the lockwasher 1802 and can influence the load necessary to move the lock washer1802 from the lock position toward the secondary lock position. Aportion 1828 of the second surface 1816 can define a stop that limitsmovement of the lock washer 1802 in a direction toward the secondarylock position (and, in some configurations, can define the secondarylock position). In the illustrated arrangement, the stop portion 1828 islocated substantially opposite the pivot point 1826 and/or near thespring 1824.

There are a number of properties, characteristics or dimensions (e.g.,materials or geometric shapes/proportions) that influence the activationlength, lock strength and the durability of the directional lockmechanism 1800. Some of these can include the clearances betweenrelative components (such as, for example, lock washer 1802 to coremember 1804 or core member 1804 to housing 1806), the contact areabetween the lock washer 1802 and the core member 1804, the angle of thelock wall 1814 or lock surface 1816, or the force and lever lengthassociated with the release mechanism 1822. In some configurations, afriction promoter is utilized to encourage initial engagement of thelock washer 1802 and the core member 1804. The friction promoter can beused to improve the initial lock activation. The friction promoter canbe any achieved using any suitable technique, including but not limitedto the use of a soft material to provide increased friction between thelock washer 1802 and the core member 1804, the use of a slightly angledrelease surface 1812 on the release wall 1810 of the lock chamber withinthe housing 1806, or the use of close tolerances between the hole in thelock washer 1802 and the core member 1804. In some configurations, thecore member 1804 can have a diameter or cross-sectional dimension ofbetween about 0.1 mm and about 8 mm, or any value or sub-range withinthat range. In some configurations, the core member 1804 may have adiameter or cross-sectional dimension greater than 8 mm.

FIG. 34 illustrates a relationship between slip force and the lock angleof a directional lock (e.g., directional locks 1800 and 1820) thatutilizes an angled lock member (e.g., lock plate or lock washer 1802).As illustrated, other factors being equal, the slip force required toachieve relative movement between the core member 1804 and the housing1806 increases as the angle Θ of the lock washer 1802 in the lockposition increases. In at least some configurations, the relationship isgenerally linear. By way of example, the graph of FIG. 34 illustratesthe change in slip force for lock angles between 10 degrees and 25degrees. The slip force varies from about 2-2.5 Newtons at 10 degrees toabout 9 Newtons at 25 degrees with a generally linear relationshipbetween those end points. The relationship between lock angle and slipforce is one factor that can be utilized to achieve desirable lockand/or slip properties of a directional lock. The lock anglesillustrated in FIG. 34 are merely exemplary. In some configurations, thelock angle can vary from just beyond zero degrees to about 45 degrees,or more. In some configurations, the lock angle is between about 10degrees and about 25 degrees, as illustrated in the graph of FIG. 34, orany particular value or sub-range within that range. The slip force, ormaximum lock force, for the directional lock 1800 or any other similarmechanism described herein, can be sufficient to inhibit undesired slipmovement of the lock (e.g., as a result of blow-off forces or normal orexpected external forces), but is not so great that desired slipmovement of the lock (e.g., to permit application of the interfaceassembly) is prevented. As discussed herein, the slip force can beselected to be above the particular operational envelope for headgearapplication, which can be related to the type of interface to be usedand/or the type of therapy, among other factors. In some configurations,the slip force is above the operational envelope by a reserve amount. Insome configurations, the slip force can be less than or equal to about65 Newtons, less than or equal to about 45 Newtons, less than or equalto about 25 Newtons, less than or equal to about 9 or 10 Newtons, or anyparticular value or sub-ranges within these ranges. In someconfigurations, the slip force can be at least about 0.5 Newtons. Insome configurations, the slip force can be at least about 0.5 Newtonsand less than or equal to about 9, 10, 25, 45 or 65 Newtons, or anyparticular value or sub-ranges within these ranges. In someconfigurations, the slip force can be about 0.5 Newtons to about 65Newtons, about 1 Newton to about 45 Newtons, about 2 Newtons to about 25Newtons, or about 2.5 Newtons to about 9 or 10 Newtons, or anyparticular value or sub-ranges within these ranges.

FIG. 35 illustrates variations in slip force that can be achieved withvariations in the biasing arrangement 1824. Other characteristics beingequal, the slip force can be varied by varying the characteristics ofthe biasing arrangement 1824 to increase or decrease the resistance tothe lock washer 1802 move from the lock position toward the secondarylock position. For example, if the biasing arrangement comprises aspring 1824, the spring rate and/or preload can be selected to vary theslip force of the directional lock 1800, 1820. FIG. 35 illustrates fourdifferent variations in the biasing arrangement 1824 that results infour different slip forces (e.g., about 2 Newtons, about 4 Newtons,about 8 Newtons and about 10-11 Netwons). Such slip forces are only byway of example and can be adjusted to any suitable level. Although acompression coil spring is illustrated in FIG. 33, other suitable typesof springs or spring-like elements (among other biasing arrangements)could also be used. In addition, the biasing arrangement 1824 could beadjustable post-manufacturing (e.g., by a caregiver or user) to allowthe slip force to be adjusted after manufacturing, such as toaccommodate user preference. For example, an adjustment mechanism couldbe provided that adjusts the preload on the spring 1828.

FIGS. 36 and 37 illustrate a self-fit interface assembly 1850 exhibitingresistance on demand. The illustrated interface assembly 1850 providesdirectional locking functionality utilizing mechanical adhesion betweena first portion of the assembly and a second portion of the assembly.Preferably, the interface assembly 1850 is constructed in a similarmanner to interfaces described herein, such as those of FIGS. 7 and 8,in that two portions of the interface assembly 1850 interact to providea first force in response to extension of the interface assembly 1850and a second, preferably lower retraction force. However, the interfaceassembly 1850 of FIGS. 36 and 37 preferably provides such directionallocking using microstructures on one or both portions that providemechanical adhesion, mechanical interlocking, Van der Waal forces orother intermolecular forces.

With reference to FIG. 36, the interface assembly 1850 preferablyincludes an interface or mask portion 1852 and a headgear portion 1854.The mask portion 1852 preferably contacts the face of a user and createsat least a substantial seal with the user's face. The headgear portion1854 extends around the user's head and supports the mask portion 1852on the user's face. With reference to FIG. 37, a portion of theinterface assembly 1850 is shown having a first portion 1856 and asecond portion 1858 that are movable relative to one another to permit alength of the headgear portion 1854 to be varied. Each of the portions1856 and 1858 can be defined by one or more of the mask portion 1852 orheadgear portion 1854, or any other component of the interface assembly1850. In some configurations, both portions 1856 and 1858 are defined byportions of the headgear portion 1854.

Preferably, one or both of the portions 1856 and 1858 includemicrostructures 1860 (FIGS. 38 and 39) that allow the portions 1856,1858 to selectively engage one another and provide a directional lockingforce. Preferably, the locking force is sufficient to inhibit or preventrelative movement of the portions 1856, 1858, or maintain a currentlength of the headgear portion 1854, in response to expected or normaloperational forces F_(N), such as one or more of blow-off forces, hosepull forces, other external forces and a reserve. The locking force canbe influenced by a force F_(P) applied to the portions 1856, 1858 in adirection generally perpendicular to the direction of relative movementtherebetween or in a generally radial direction if the interfaceassembly 1850 is considered as or in the general shape of a circle (suchas when fitted on a user). Thus, the locking force can be increased whenthe user's head applied an outward force to the inner one of theportions 1856, 1858.

As described above in connection with other interface assemblies, theinterface assembly 1850 can exhibit a first level of resistance toextension in the absence of a perpendicular or radial force on theportions 1856, 1858 and a second, preferably higher level of resistanceto extension in the presence of a perpendicular or radial force on theportions 1856, 1858. Accordingly, the headgear portion 1854 can bestretched at the first level of resistance and then fitted to the user'shead. Once fitted, the headgear portion 1854 can provide a second,higher level of resistance to extension, which acts to resist blow-offor other forces tending to extend the headgear portion 1854. Preferably,the force tending to resist retraction of the headgear portion 1854(and, thus, the force applied to the user's head) is lower than at leastthe second level of resistance, and may be lower than the first level ofresistance to extension, to improve user comfort.

The microstructures 1860 can be of any suitable arrangement to provide adesired level of resistance to relative movement of the portions 1856,1858 in either or both of extension and retraction. Preferably, in someconfigurations, the microstructures 1860 are directional or result indifferent levels or resistance depending on the direction of relativemovement. As illustrated in FIG. 38, one suitable microstructurearrangement 1860 can comprise a plurality of fibers, such as microfibersor nanofibers, which can be produced using an electrospinning processand any suitable material, such a polymeric materials. Other suitablemethods and/or materials may also be used. The fibers can be oriented ina suitable manner to provide directional properties, if desired.

As illustrated in FIG. 39, another suitable microstructure can comprisea plurality of geometric shapes, such as a plurality of ridges, teeth orscale-like protrusions 1862, for example. The protrusions 1862 can eachhave a base 1864 and an edge 1866 that is generally opposite the base1864. Each of the portions 1856, 1858 can employ such protrusions 1862or one portion 1856, 1858 can employ protrusions 1862 and the otherportion 1856, 1858 can employ other types of complementary structuresthat are suitable to engage the protrusions 1862. Preferably, theprotrusions 1862 are oriented to provide the portions 1856, 1858 withdirectional locking or directional resistance to relative movement. Forexample, the protrusions 1862 could be oriented at an oblique anglerelative to the surface on which the protrusions 1862 are supportedand/or relative to the direction of movement. Thus, in response tomovement in one direction, the protrusions 1862 could slide over oneanother with a lower level of resistance and, in response to movement inthe other direction, the protrusions 1862 could engage one another toinhibit or prevent relative movement and provide a locking function. Theprotrusions 1862 can be arranged in any suitable manner (e.g., one ormore rows). The protrusions 1862 can be constructed from any suitablematerial (e.g., polymer) by any suitable process (e.g., micro machiningor micro molding techniques).

FIGS. 40-42 illustrate another adjustment mechanism 1900 having variabledirectional properties, which can be utilized in a self-fit interfaceassembly. The illustrated adjustment mechanism 1900 provides directionallocking functionality and, thus, can be referred to as a directionallocking mechanism or, simply, a directional lock. The directional lock1900 of FIGS. 40-42 is similar in general operational principles to thearrangements of FIGS. 16, 21, 32 and 33 in that a lock component ormember 1902 (e.g., lock plate) is movable between a first, lowerresistance or release position and a second, higher resistance or lockposition. Features or details not described with respect to thedirectional lock 1900 of FIGS. 40-42 can be the same as or similar tocorresponding features of the arrangements of FIGS. 16, 21, 32 and 33,or can be of another suitable configuration.

The directional lock 1900 preferably includes a core member in the formof a flat strap 1904, which functions similar to the core member of theprior arrangements. The directional lock 1900 preferably also includesan enclosure or a housing 1906, which can be similar in construction andfunction to the housing of the prior arrangements. Thus, the lock plate1902 is supported within the housing 1906 for movement between the firstposition and the second position. Preferably, the housing 1906 includesa first wall 1910 having a first stop surface 1912 that supports thelock plate 1902 in the first position, which preferably is the lowerresistance or release position. The housing 1906 preferably alsoincludes a second wall 1914 having a second stop surface 1916 thatsupports the lock plate 1902 in the second position, which preferably isthe higher resistance or lock position.

Preferably, the lock plate 1902 is positioned generally perpendicular toa longitudinal axis of the strap 1904 positioned within the lock cavityof the housing 1906 in the first, lower resistance or release positionsuch that the opening or hole of the lock plate 1902 is positionedgenerally parallel to or aligned with the strap 1904. Preferably, thelock plate 1902 is positioned at an oblique angle relative to thelongitudinal axis of a portion of the strap 1904 positioned within thelock cavity of the housing 1906 in the second, higher resistance or lockposition such that the opening or hole of the lock plate 1902 ispositioned at an oblique angle to the strap 1904. Thus, in someconfigurations, the first stop surface 1912 can be generallyperpendicular to the strap 1904 positioned within the lock cavity of thehousing 1906 (and/or the openings in the housing 1906 through which thestrap 1904 passes) and the second stop surface 1916 can be positioned atan oblique angle Θ relative to the strap 1904 (and/or the openings inthe housing 1906 through which the core member 1904 passes). Asdiscussed below, the angle of the second stop surface 1916 or the lockplate 1902 when contacting the second stop surface 1916 can be selectedto achieve a desired maximum lock force or magnitude of resistance whenthe lock washer 1902 is in the lock position. If desired, a releasemechanism can be provided similar to the release mechanism 1822 of FIG.33.

As in the prior arrangements, the strap 1904 can be coupled to or form afirst portion of the associated interface assembly and the housing 1906can be coupled to or form a second portion of the interface assemblysuch that a length or circumference of the interface assembly can beadjusted by relative movement of the strap 1904 and the housing 1906.Advantageously, the strap 1904 is anisotropic with respect to one ormore properties. For example, the strap 1904 is more flexible whenflexing or bending in a width direction than when bending in a heightdirection. Accordingly, the strap 1904 can flex in a direction toconform to the user's head, but resists flex in the height direction toprovide support to the interface assembly and inhibit undesired movementof the mask portion. In addition, the directional lock 1900 comprisingthe strap 1904 is well-suited for use in portions of the interfaceassembly that contact the user's head, such as sides, rear or topportions of the headgear strap, for example, with possibly greatercomfort than interfaces having generally cylindrical core members.However, the directional lock 1900 can also be used in other portions orlocations of the interface assembly, such as on one or both sideportions of the headgear between the portions than contact the user'shead and the mask portion.

The illustrated directional lock 1900 includes an activation mechanism1920 that facilitates movement of the lock plate 1902 to increase thesensitivity of the directional lock 1900. Such an activation mechanism1920 can hasten movement of the lock plate 1902 to or from a lockposition or a release position to improve the time or distance ofrelative movement required to transition between a lock position and arelease position of the directional lock 1900. In addition or in thealternative, the activation mechanism 1920 can decrease the sensitivityof the directional lock 1900 to variations in component dimensions(e.g., dimensions of interacting portions of the lock plate 1902 orstrap 1904) such that the component tolerances can be greater, whilemaintaining a desirable level of functionality, thereby reducing thecost of the directional lock 1900.

In some configurations, one of the lock plate 1902 and the strap 1904can include an engagement feature 1922 that facilitates engagement withthe other of the lock plate 1902 and the strap 1904. In the illustratedarrangement, the strap 1904 includes an engagement feature 1922 thatfacilitates frictional engagement with the lock plate 1902. Theengagement feature 1922 can comprise a portion of the strap 1904 havingparticular dimensions, surface features or materials that enhanceengagement with the lock plate 1902. For example, with reference to FIG.42, a width of the engagement feature 1922 can be greater than a widthof a remainder of the strap 1904. In addition or in the alternative, theengagement feature 1922 can comprise a different material or surfacefinish that has improved frictional characteristics relative to aremainder of the strap 1904 to enhance frictional engagement between thelock plate 1902 and the strap 1904. In the illustrated arrangement, theengagement feature 1922 is a silicone material portion that is keyed tothe remainder of the strap 1904, which can be constructed of a suitableplastic material. However, other suitable materials can also be used forthe engagement feature 1922 or the remainder of the strap 1904. Themechanical interference between the interacting lobes of the engagementfeature 1922 and the remainder of the strap 1904 inhibits separation ofthe different materials. Other suitable arrangements, materials orconstructions of the strap 1904 having an engagement feature 1922 canalso be used.

Preferably, the engagement feature 1922 acts on a different surface(s)of the lock plate 1902 than a surface(s) that provides a primary lockingfunction. For example, because the engagement feature 1922 has anincreased width relative to the remainder of the strap 1904, theengagement feature 1922 acts substantially or primarily on side (height)surfaces of the strap 1904 while the substantial or primary lockingfunction is accomplished by the top and bottom (width) surfaces. Atleast partial separation of the locking and engagement functionalitiespermits each to be optimized separately. Thus, the sensitivity of thedirectional lock 1900 can be varied to achieve a desired level ofsensitivity and the lock force can be separately varied to achieve adesired level of locking without causing a substantial negative impacton one another.

FIGS. 43-45 illustrate an interface assembly 1950 having self-fitfunctionality similar to other interface assemblies described herein.FIGS. 43-45 illustrate the interface assembly 1950 in various positionswithin a fitment process. FIG. 43 illustrates the interface assembly1950 partially fitted to a user. FIG. 45 illustrates the interfaceassembly 1950 fully fitted to a user and FIG. 44 illustrates theinterface assembly 1950 in between the positions of FIGS. 43 and 45.

In general, the interface assembly 1950 comprises an interface portion1952, such as a mask, and a headgear portion 1954. The headgear portion1954 can include a rear portion 1956 that contacts the user's head andincludes one or more straps. In the illustrated arrangement, the rearportion 1956 includes multiple straps: one that passes around the rearof the head and one that passes over the crown of the head. However, anysuitable number of straps can be provided. The headgear portion 1954also includes a pair of side straps 1958 that extend between andpreferably connect the rear portion 1956 and the mask 1952. In theillustrated arrangement, each of the side straps 1958 comprises aportion or all of a directional locking arrangement 1960, which providesor otherwise facilitates the self-fit functionality. Optionally, themask 1952 can carry or include a portion of the directional lockingarrangement 1960. In other arrangements, other portions of the interfaceassembly 1950 (e.g., the rear portion 1956 of the headgear portion 1954and/or the mask 1952) can include a portion or an entirety of adirectional locking arrangement, in addition or in the alternative tothe side straps 1958. Each side strap 1958 can be substantially similaror identical in construction and operation.

As described above in connection to other interface assemblies,preferably the interface assembly 1950 provides self-fit or directionalfunctionality in that it permits the interface assembly 1950 to extendfor application, retract to adjust to the particular user's head sizeand then lock to inhibit or prevent extension in response to expected ornormal forces, such as one or more of CPAP blow-off forces, hose pullforces and a reserve. Preferably, the directional lock 1960 has lowerresistance to forces tending to retract the interface assembly 1950,headgear portion 1954 or side strap 1958 and a higher resistance toforces tending to extend the interface assembly 1950, headgear portion1954 or side strap 1958 such that the retention force applied to theuser's head by the interface assembly 1950 is less than the lockingforce that inhibits extension of the interface assembly 1950. In someconfigurations, the retention force is below the operational envelopefor the interface assembly 1950 and the locking force is above theoperational envelope, as described herein with reference to FIGS. 2-5.

FIGS. 46-48 illustrate the directional lock arrangement 1960incorporating the side strap 1958 separate from the interface assembly1950 of FIGS. 43-45. The directional lock arrangement 1960 generallycomprises a lock portion or lock 1962, a core member 1964 and an elasticstrap 1966. The elastic strap 1966 and at least a portion of the coremember 1964 form at least a portion of the side strap 1958. The lock1962 can form a portion of the side strap 1958 and, preferably, attachesto the mask 1952 or can be a portion of the mask 1952.

The core member 1964 can be connected at one end to the elastic strap1966. Preferably, the core member 1964 passes through the lock 1962. Afree end of the core member 1964 can be positioned within a conduit ortube 1968, which can reside in, be carried by or be formed by the mask1952. The elastic sleeve 1966 preferably provides a force tending topush the core member 1964 through the lock 1962 in a direction such thata larger portion of the core member 1964 resides in the tube 1968.Therefore, the elastic sleeve 1966 (or the pair of elastic sleeves 1966assuming a pair of side straps 1958) preferably provides some or all ofa force tending to retract the interface assembly 1950. Preferably, thecore member 1964 has sufficient stiffness or column strength to bepushed through the lock 1962 without significant buckling. In someconfigurations, other retraction mechanisms could be provided to providea retraction force in addition or in the alternative of the elasticstrap(s) 1966. For example, a biasing element could be coupled to a freeend of the core member 1964 to pull the core member 1964 through thelock 1962, which could provide all of the retraction force (in whichcase the strap 1966 could be omitted or could be non-elastic) or couldoperate in concert with the elastic strap 1966. In some configurations,a biasing element could connect the free ends of both core members 1964to provide some or all of the retraction force to both of the sidestraps 1958. In still further configurations, the associated headgearmay not provide a retraction force. For example, the headgear may bemanually retracted to a desired circumference to fit the user's head.

The lock 1962 operates in accordance with the general principlesdescribed above with reference to other directional lockingarrangements, such as those of FIGS. 16, 21, 32, 33 and 40-42.Accordingly, details not discussed in connection with FIGS. 46-48 can beassumed to be similar or identical to the same or corresponding featuresin those arrangements, or can be of any other suitable arrangement.

The lock 1962 preferably includes a housing 1970 and a lock member orlock element 1972. In the illustrated arrangement, the lock element 1972is formed as unitary structure of single piece with at least a portionof the housing 1970 and, preferably, with portions that define theopenings through which the core member 1964 passes through the housing1970. The housing 1970 may have additional portions that, for example,enclose or protect the lock element 1972 or facilitate attachment to themask 1952 and/or the elastic strap 1966.

The lock element 1972 functions in manner similar to the lock members(e.g., lock washers and lock plates) described elsewhere herein. Thatis, preferably the lock element 1972 defines an opening through whichthe core member 1964 passes. The lock element 1972 is moveable between arelease position and a lock position to vary a resistance to movement ofthe core member 1964 relative to the housing 1970. Preferably, theresistance to movement of the core member 1964 tending to extend thelength of the elastic strap 1966 is greater than the resistance tomovement of the core member 1964 tending to retract the length of theelastic strap 1966. Accordingly, the retraction force provided by theelastic strap 1966 (or other components of the interface assembly 1950)can be relatively light or of a relatively low magnitude to improvepatient comfort and the lock element 1972 can permit the interfaceassembly 1950 to resist extension without reliance on the force producedby the elastic strap 1966. Thus, the retention force of the elasticstrap 1966 can be tuned for patient comfort without needing to handleblow-off or other external forces tending to extend the interfaceassembly 1950.

Similar to the arrangements described elsewhere herein, preferably,surfaces of the lock element 1972 that define or surround the openingthrough which the core member 1964 passes engages the core member 1964in the lock position to provide a level of resistance to movement of thecore member 1964 to inhibit or prevent extension of the elastic strap1966. However, instead of being controlled by surfaces of the housing,the lock element 1972 is coupled to the housing 1970 by a curved portionor a living hinge 1974 and the movement of the lock element 1972 iscontrolled by the properties of the living hinge 1974. That is, the lockelement 1972 and the living hinge 1974 are defined by a curved armportion that extends from the housing 1970 and has a free end. A relaxedposition of the lock element 1972 can define the release position, whichmay be influenced by the presence of the core member 1964 passingthrough the lock element 1972. That is, the release position may not bethe same as the relaxed position of the lock element 1972 in anunassembled state without the core member 1964. Movement or attemptedmovement of the core member 1964 in a direction tending to extend thelength of the elastic strap 1966 (to the left in the illustratedorientation) deflects the lock element 1972 toward the lock position toinhibit or prevent extension of the elastic strap 1966. The dimensions,material properties or other characteristics of the living hinge 1974influence the lock force of the lock 1962. In some configurations, thelock force is related to the angle of the lock element 1972, asdescribed elsewhere herein (see, for example, FIG. 34 and the relateddisclosure).

In some configurations, limited movement of the core member 1964 canoccur as the lock element 1972 transitions from the release position tothe lock position. Accordingly, the retraction force provided by theelastic strap 1966 (or other biasing element(s)) preferably provides aforce sufficient to maintain at least a substantial seal of the mask1952 or other interface after movement of the core member 1964 as aresult of the lock element 1972 moving to the lock position. Preferably,the lock 1962 is configured such that the distance that the core member1964 is permitted to move is relatively small.

FIGS. 46-48 illustrate the directional lock arrangement 1960 in variouspositions. FIG. 46 illustrates the directional lock arrangement 1960 ina relaxed or resting position in which the elastic strap 1966 isretracted and has pushed a maximum amount of the core member 1964 intothe tube 1968. The lock element 1972 is in the release position.

FIG. 47 illustrates the directional lock arrangement 1960 in an extendedposition, which could occur during the application phase of the fitmentprocess. The extension of the elastic strap 1966 has pulled a portion ofthe core member 1964 out of the tube 1968 against resistance offered bythe lock 1962 as a result of the lock element 1972 moving to or towardthe lock position such that a minimum amount of the core member 1964 islocated within the tube 1968. Once the extended position has beenreached and relative movement between the housing 1970 and the coremember 1964 has ceased, the lock element 1972 may remain in the lockposition, may return to the release position or may be positionedsomewhere in between depending on a variety of factors, such as thespring force of the living hinge 1974, the relative proportions of thecore member 1964 and the opening in the lock element 1972 and thefrictional force between the core member 1964 and the lock element 1972.

FIG. 48 illustrates the directional lock arrangement 1960 in anoperational position having a length between the relaxed position andthe extended position, such as when fitted on the head of a user.Compared to the extended position, the retention force of the elasticstrap 1966 has pushed a greater amount of the core member 1964 into thetube 1968 in the operational position against resistance offered by thelock element 1972 in the release position, which preferably issubstantially lower than the resistance to extension. The lock element1972 can be in the lock position, the release position or may bepositioned somewhere in between, as described above. However, inresponse to extension of the directional lock arrangement 1960 or forcestending to extend the directional lock arrangement 1960, the lockelement 1972 moves to or remains in (depending on the initial position)the lock position to provide resistance to extension due to expected ornormal operational forces. The directional lock arrangement 1960 can befurther extended in response to, for example, user-applied force toallow the interface assembly 1950 to be removed.

FIGS. 49-51 illustrate a portion of the elastic strap 1966 of thedirectional lock arrangement 1960 of FIGS. 46-48. The illustratedelastic strap 1966 is of a tubular construction and includes an interiorpassage, which can accommodate the core member 1964. Thus, the coremember 1964 can move within the elastic strap 1966 without rubbingagainst the user or other objects. Preferably, the elastic strap is abraid of multiple individual strands or yarns (fibers) of any suitablematerial in any suitable type of weave. The individual fibers can bewoven such that adjacent fibers or groups of fibers have a particularinitial angled orientation relative to one another, as illustrated inFIG. 49. Preferably, the initial angled orientation permits the braidcan be compressed and extended relative to the initial angledorientation, as illustrated in FIGS. 50 and 51, respectively. Thus, theinitial angled orientation can be described as an intermediate angledorientation. The amount of compression and extension relative to theinitial orientation can be the same or can be different from oneanother.

Preferably, as described above, the strap 1966 includes a biasingarrangement that biases the strap 1966 toward or to the compressedposition. Accordingly, the strap 1966 is referred to as an elastic strap1966. The biasing arrangement can be of any suitable construction, suchas incorporating one or more elastic fibers within the braid.Preferably, the maximum extension of the braid is selected to be lessthan the maximum extension (or other range of movement) of the biasingarrangement to avoid damage to the biasing arrangement upon maximumextension. In some configurations, the braid limits maximum extension ofthe biasing arrangement from reaching plastic deformation and maintainsthe range of extension movement within the elastic range of movement ofthe biasing arrangement, such as elastic elongation of the elasticfibers. The braid can also provide an end stop to movement of the coremember 1964 to prevent the core member 1964 from being pulled throughthe lock 1962. That is, preferably, in full extension of the braid, aportion of the core member 1964 remains within the lock 1962.

With reference to FIGS. 52-54, in some configurations, one or moreelastic fibers 1980 can be integrated into the braid during the weavingprocess. FIG. 52 is a schematic illustration of a machine and processfor creating the braided elastic strap 1966. The machine includesmultiple spindles 1982 having a plurality of cavities defined betweenradial projections or teeth. Adjacent spindles 1982 rotation in oppositedirections as indicated by the arrows and pass a preferably relativelyinelastic fiber or groups of fibers 1984 from one spindle 1982 to thenext. Another fiber or group of fibers 1984 move from one spindle 1982to the next in the opposite direction to weave the two fibers or groupsof fibers 1984 together. Elastic fibers 1980 can be passed through thecenters of the spindles 1982 such that the elastic fibers 1980 areintegrated into the braid, as illustrated in FIG. 53. FIG. 54illustrates the elastic strap 1966 if the tubular member were cut in alongitudinal direction and laid flat.

FIG. 55 illustrates a rear portion 1956 of a headgear assembly 1954 thatcan be used with the interface assembly 1950, other interface assembliesdisclosed herein or any other suitable interface. The rear portion 1956of the headgear assembly 1954 illustrated in FIG. 55 comprises a lowerrear section 1990 in the form of an interrupted or segmented strap thatseparates a load or provided a non-uniform load acting on the user'shead, in contrast to a non-segmented strap that places a load across anentire length of the strap. That is, the lower rear section 1990 has afirst portion 1990 a and a second portion 1990 b, which preferably areinterrupted and/or spaced apart and can be connected by a coupling 1992,such as one or more straps or laces or a weakened portion of the section1990. The coupling 1992 can be relatively or substantially inelastic tosubstantially fix a relative position of the first portion 1990 a andthe second portion 1990 b relative to a longitudinal axis of the section1990 (the length of the section 1990), but can permit relative movementof the first portion 1990 a and the second portion 1990 b in aperpendicular or rotational direction relative to the longitudinal axis.Such an arrangement can be referred to as an articulable connector.Preferably, the first portion 1990 a and the second portion 1990 b formoccipital pads that engage the user's head on or near the occipitalbone. A space between the first portion 1990 a and the second portion1990 b can be located generally at the occipital protuberance in acircumferential direction and the lower real section 1990 can be at orbelow the occipital protuberance in a height direction. Preferably, therear portion 1956 also comprises an upper rear section 1994 that extendsover the crown of the user's head. Ends of the lower rear section 1990and the upper rear section 1994 join one another at a location generallyabove each ear of the user.

FIG. 56 illustrates a rear portion 1956 of a headgear assembly that issimilar to the rear portion 1956 of FIG. 55. Accordingly, details of therear portion 1956 of FIG. 56 not discussed can be assumed to be the sameas or similar to the corresponding elements of the rear portion 1956 ofFIG. 55, or can be of any other suitable arrangement. The coupling 1992of the rear portion 1956 of FIG. 56 comprises an articulable connector,such as a material strap, which can be elastic or substantiallyinelastic. Preferably, the coupling 1992 permits relative rotationalmovement between the first portion 1990 a and the second portion 1990 babout a longitudinal axis of the strap to allow the lower rear section1990 to better conform to the shape of the user's head, in particular,the occipital bone geometry.

Advantageously, the rear portions 1956 of FIGS. 55 and 56 providecomfort for the user while also securing the mask or other patientinterface in place on the user's head. The interrupted lower rearsection 1990 avoids placing excessive pressure on the occipitalprotuberance. Such an interrupted arrangement can also or alternativelybe provided in the upper rear section 1994. Either of the rear portions1956 of FIGS. 55 and 56 could also incorporate one or more directionallock assemblies, such as any of those disclosed herein. For example, thecoupling 1992 could be configured as a directional lock assembly. Adirectional lock assembly could also be integrated into either or bothof the lower rear section 1990 and the upper rear section 1994. Forexample, the flat strap arrangement of FIGS. 40-42 could be integratedinto either or both of the first portion 1990 a and the second portion1990 b.

FIGS. 57 and 58 illustrate two versions of an interface assembly, whichcan be substantially similar to the interface assembly 1950 and relatedcomponents described in connection with FIGS. 43-56. Accordingly,details of the rear portion interface assemblies 1950 of FIGS. 57 and 58not discussed can be assumed to be the same as or similar to thecorresponding elements of the interface assembly 1950 and relatedcomponents described in connection with FIGS. 43-56, or can be of anyother suitable arrangement. In each interface assembly 1950, each sidestrap 1958 (which can incorporate a directional lock or can be a fixedlength) is coupled to the rear portion 1956 of the headgear assembly1954 at a point 1996 located near the user's ear. Preferably, the point1996 is located forward of the ear and at (e.g., generally in line with)or near the upper location at which the outer ear is joined to the head(the top of the base of the outer ear). The side strap 1958 extends fromthe point 1996 to the mask 1952 or other interface. In the interfaceassembly 1950 of FIG. 57, a single side strap 1958 on each side of theinterface assembly 1950 extends from the point 1996 to the mask 1952. Inthe interface assembly 1950 of FIG. 58, a pair of side straps 1958 oneach side of the interface assembly 1950 extends from the point 1996 tospaced-apart locations on the mask 1952 to provide a triangulatedarrangement, which in at least some cases increases the stability of themask 1952. Preferably, a rearward projection of the side strap(s) 1958passes between the upper and lower straps of the rear portion 1956 ofthe headgear assembly 1954 such that loads are divided between the upperand lower straps. Examples and further details of such an arrangementare disclosed in Applicant's U.S. Patent Publication No. 2013/0074845,the entirety of which is incorporated by reference herein. As discussedabove, if desired, one or more directional locks can be incorporatedinto the interface assemblies 1950 of FIGS. 57 and 58 at any suitablelocation, such as those described herein.

In any of the headgear embodiments described above, additional strapscould be included to provide additional stability, such as but notlimited to a crown strap or additional back strap.

FIG. 59 illustrates a lock arrangement 1962 that is substantiallysimilar to the lock arrangement 1962 of FIGS. 46-48. Accordingly,details of the lock arrangement 1962 of FIG. 59 not discussed can beassumed to be the same as or similar to the corresponding elements ofthe lock arrangement 1962 of FIGS. 46-48, or can be of any othersuitable arrangement. The lock arrangement 1962 of FIG. 59 is a modulardesign that allows directional locking technology to be easilyincorporated into a range of respiratory masks or other user interfaces.

The lock arrangement 1962 includes a housing or body portion 1970, alocking element 1972 and a living hinge 1974 that connects the lockingelement 1972 to the body portion 1970. The body portion 1970 includes afirst end portion 2000 and a second end portion 2002. A generallyU-shaped connecting bridge 2004 extends between the first end portion2000 and the second end portion 2002 and provides space therebetween toaccommodate the locking element 1972. Preferably, each end portion 2000,2002 is generally tubular or cylindrical in shape and defines alongitudinal passage that accommodates a core member. The lockingelement 1972 also includes a hole 2006 that permits passage of the coremember. Preferably, the end portions 2000, 2002, the connecting bridge2004, the locking element 1972 and the living hinge 1974 are of aone-piece construction.

FIG. 60 illustrates the lock arrangement 1962 of FIG. 59 incorporatedinto a patient interface assembly, such as a mask 1952. The illustratedmask 1952 includes walls 2010 defining a pocket 2012, which receives thelock arrangement 1962. The walls 2010 can include recesses or openingsthat receive the end portions 2000, 2002 of the lock arrangement 1962,such as in a male/female coupling. In the illustrated arrangement, theend portions 2000, 2002 define male portions that can be received infemale portions (e.g., recesses or openings) of the mask 1952. Thus, thewalls 2010 and or pocket 2012 can hold the lock arrangement 1962 inplace and provide further support to the body portion 1970. In otherwords, the walls 2010 can function as a structural housing or enclosurefor the lock arrangement 1962. The first end portion 2000, the mask 1952or both can be configured to connect to a strap 1966, such as an elasticstrap. The second end portion 2002, the mask 1952 or both can beconfigured to support a tube 1968 that houses a free end portion of acore member 1964. Preferably, the mask 1952 is configured to accommodatethe tube 1968, which can include being specifically configured toreceive the tube 1968 (or having an integrated tube) or simply beingcompatible with the presence of the tube 1968 (such as possessingsufficient open or available space to receive the tube 1968).

Interface assemblies disclosed herein can utilize a generally elasticportion and a generally inelastic portion, which cooperate to define atleast a portion of a loop or circumference of the interface assembly.The elastic portion allows the size of the interface assembly to vary.The inelastic portion can form a structural portion of the loop orcircumference or can simply be utilized for directional lockingpurposes, or both. Regardless, it is often necessary or desirable toallow for extension or expansion of the interface assembly and thenaccumulation of the inelastic portion during retraction. For example, inthe interface assembly of FIGS. 43-54, the core member 1964 moves withextension of the elastic strap 1966 and the tube 1968 acts as anaccumulator to receive an excess portion of the core member 1964,depending on the instantaneous amount of extension.

Other arrangements are possible to provide for expansion andaccumulation of a combined elastic/inelastic interface assemblies orheadgear arrangements. FIGS. 61 and 62 illustrate a headgear arrangement2050 including a tubular elastic element 2052 defining portion of a loopor circumference of the headgear arrangement 2050 and having a first end2054 and a second end 2056. The illustrated tubular elastic element 2052forms approximately one-half of the length of the loop; however, inother configurations, the elastic tubular element 2052 could form alesser or greater proportion of the loop.

The headgear arrangement 2050 also includes a generally inelasticelement 2060 that forms at least a portion of the loop and preferably isarranged in parallel with the elastic element 2052. In the illustratedarrangement, the inelastic element 2060 extends along more than theentire length of the loop. That is, preferably, a first end 2062 of theinelastic element 2060 is secured to the first end 2054 of the elasticelement 2052 and a second end 2064 of the inelastic element 2060 issecured to the second end 2056 of the elastic element 2052. From thefirst end 2062, the inelastic element 2060 extends outside of theelastic element 2052, into the second end 2056 of the elastic element2052, through the interior of the elastic element 2052, out of the firstend 2054 of the elastic element and then, as described above, the secondend 2064 of the inelastic element 2060 is secured to the second end 2056of the elastic element 2052. Thus, two overlapping lengths or sectionsof the inelastic element 2060 are provided outside of the elasticelement 2052. The headgear arrangement 2050 preferably includes aconnector 2066 that connects the headgear arrangement 2050 to aninterface, such as a mask. In the illustrated arrangement, the connector2066 is a tubular member through which both external sections of theinelastic element 2060 extend. The connector 2066 can connect to themask in any suitable manner, including being clipped onto or integratedinto the mask, for example.

To extend in length, more of the inelastic element 2060 is pulled intothe interior of the elastic element 2052 (or, viewed another way, theelastic element 2052 stretches to cover a greater portion of theinelastic element 2060). As a result, the length of the overlappingsections of the inelastic element 2060 is reduced such that theeffective length of the circumference of the inelastic element 2060 (andthe headgear arrangement 2050) is increased. To retract in length, theopposite action occurs so that a lesser portion of the inelastic element2060 is positioned within the elastic element 2052 and a length of theoverlapping sections of the inelastic element 2060 is increased.Relatively retracted and relatively extended positions are illustratedin FIGS. 63 and 64.

If directional locking is desired, one or more directional locks, suchas any of those described herein, can be incorporated into the headgeararrangement 2050. FIG. 65 illustrates one example placement fordirectional locks at one or both ends 2054, 2056 of the elastic element2052, which can act on relative movement between the ends 2054, 2056 andthe inelastic element 2060. FIG. 66 illustrates an alternative oradditional placement for directional locks, such as at either end of theconnector 2066 and acting on relative movement between the inelasticelement 2060 and the connector 2066.

FIGS. 67 and 68 illustrate another headgear arrangement 2070 thatincludes an elastic element 2052 and an inelastic element 2060. However,whereas the headgear arrangement 2050 is an endless loop oruninterrupted circle, the headgear arrangement 2070 is an interrupteddesign having a first end portion 2072 and a second end portion 2074,which can be coupled to respective sides of a patient interface, such asa mask 2076 (FIG. 68). Thus, the first end portion 2072 and the secondend portion 2074 can each define an engagement portion, such as a hookor clip, for example, which permits the end portion 2072 or 2074 to becoupled to the mask 2076 or other interface. However, each of thesearrangements can be considered to substantially surround the head of auser because ends of the interrupted design are interconnected by thepatient interface.

In the headgear arrangement 2070 of FIGS. 67 and 68, the externalsections of the inelastic element 2060 double back on themselves and aresecured to the same side of the elastic element 2052 instead ofoverlapping one another and being secured to the opposite sides of theelastic element 2052, as in the headgear arrangement 2050 of FIGS. 61and 62. Each of the end portions 2072, 2074 can include a pulley, whichcan be fixed or free (rotatable), or another suitable arrangement toreverse a direction of the external section of the inelastic element2060. The operation of the headgear arrangement 2070 is substantiallysimilar to the headgear arrangement 2050 in that a length of theexternal sections is increased to reduce the length of the headgeararrangement 2070, as illustrated in FIG. 69, or decreased to increasethe length of the headgear arrangement 2070, as illustrated in FIG. 70.In addition, more or less of the inelastic element 2060 is exposed orcovered by the elastic element 2052 as a result of a change in overalllength of the headgear arrangement 2070.

If directional locking is desired, one or more directional locks, suchas any of those described herein, can be incorporated into the headgeararrangement 2070. FIG. 71 illustrates one example placement fordirectional locks at one or both ends 2054, 2056 of the elastic element2052, which can act on relative movement between the ends 2054, 2056 andthe inelastic element 2060. FIG. 72 illustrates an alternative oradditional placement for directional locks, such as on either one orboth of the first end portion 2072 and the second end portion 2074. Insuch an arrangement, the directional lock can act on relative movementbetween the inelastic element 2060 and the first end portion 2072 or thesecond end portion 2074.

As discussed herein, embodiments of the present interface assemblieswith balanced fit properties can be used with, or can be modified foruse with, cannulas or other similar interfaces that do not create a sealwith the user's face and, therefore, do not develop blow-off forces.FIG. 73 compares several force profiles and illustrates a balanced fitpoint of a cannula 2090 versus a balanced fit point of a CPAP mask 2092within a one-way friction force profile 2098, which is an example forceprofile that can be provided by the interface assemblies describedherein. As illustrated, a balanced fit generally occurs at differentforces for CPAP and cannula systems. For a cannula or similarnon-sealing system, the balanced-fit point 2090 occurs once the headcircumference has been matched because no blow-off forces, or at leastno substantial blow-off forces, are developed. In a CPAP system, thebalanced-fit point 2092 occurs once head circumference and blow-offforces have been matched. For a CPAP system, the headgear preferablyprovides for a balanced fit point 2092 that could occur anywhere withinthe CPAP mask system operating envelope 2080. For a cannula system, thebalanced fit point 2090 preferably will occur somewhere along thecannula balanced fit line 2082, which is defined by the lower force lineof the one-way friction force profile 2098. The cannula balanced fitline 2082 shows that the force required to hold a cannula in place on auser's face preferably will be lower than the minimum force required tohold a CPAP mask in place and will generally fall within a smaller rangebecause of the lack of blow-off forces.

FIG. 73 also compares the force profiles of a high force elastic strap2094 and a low force elastic strap 2096 with the high hysteresis one-wayfriction force profile 2098. Low force elastic straps can be used inconjunction with cannulas to provide a comfortable fit for the user thatis capable of overcoming just the weight of the cannula. However, sucharrangements generally will not be capable of accommodating anysignificant external forces such as hose pull. In order to accommodateexternal forces, or blow-off forces in the case of CPAP treatment, ahigh force elastic strap generally is required. The force applied by ahigh force elastic strap headgear generally should be sufficient toaccommodate the highest possible force that is expected to be applied tothe mask, whilst on the smallest possible head size (shown by the shadedmask system operating envelope 2080). This, however, has thedisadvantage of applying a higher than necessary minimum force whenthere is low blow-off forces and/or no external forces, which can beuncomfortable for users. The one-way friction force profile 2098 showsthat it provides the benefits of both the high and low force elasticstraps. That is, the one-way friction force profile 2098 provides highresistance to elongation and low forces in the absence of blow-off orexternal forces.

FIG. 74 illustrates a directional lock 2100 that involves principles ofoperation similar to other directional locks disclosed herein, such asthe directional locks of FIGS. 16, 21, 32, 33, 40-42 and 43-51, forexample and without limitation. However, the directional lock 2100illustrated in FIG. 74 is a dual stage directional lock, whichincorporates two different lock stages 2102, 2104. Preferably, the twolock stages 2102, 2104 have locking behaviour or characteristics thatare different from one another. For example, the first lock stage 2102can be a quick activation lock, which moves more quickly between arelease position and a lock position than the second lock stage 2104.The second lock stage 2014 can be a high force lock, which provides ahigher lock or yield force than the first lock stage 2102. Such anarrangement can allow optimization of both activation and lock forcecharacteristics of the directional lock 2100. Features or details notdescribed with respect to the directional lock 2100 can be the same orsimilar to corresponding features or details of the arrangements of FIG.16, 21, 32, 33, 40-42 or 43-51, or can be of another suitableconfiguration.

The illustrated directional lock 2100 includes a core member 2110 (e.g.,a core wire) that passes through a lock body, which can be any suitableenclosure or housing 2112. The housing 2112 defines two lock chambers2114 and 2116. Each lock chamber 2114, 2116 has a lock member 2120, 2122(e.g., a lock washer) positioned therein. As described previously, thecore member 2110 passes through an opening in the lock members 2120,2122. Each lock chamber 2114, 2116 has a first stop surface 2114 a, 2116a spaced from a second stop surface 2114 b, 2116 b in a direction ofmovement of the core member 2110 to limit movement of the respectivelock members 2120, 2122. The stop surfaces 2114 a, 2116 a, 2114 b, 2116b can be defined by a wall of the housing 2112 or any other structuresuitable to limit movement of the lock members 2120, 2122.

The lock members 2120, 2122 are movable between a lock position, inwhich resistance to movement of the core member 2110 is increased, and arelease position, in which resistance to movement of the core member2110 is reduced. In some configurations, movement of the core member2110 moves the lock members 2120, 2122 between the lock position and therelease position. In the illustrated arrangement, unlike thepreviously-described arrangements, the stop surfaces 2114 a, 2116 a,2114 b, 2116 b are flat or planar and the lock members 2120, 2122 arebent to define an effective lock angle that operates in a manner similarto the previously-described arrangements. In particular, an opening ofthe lock members 2120, 2122 through which the core member 2110 passescan be generally aligned with an axis of the core member 2110 in therelease position to reduce friction and, thus, lock force and theopening can be canted or angled in the lock position to increasefriction and, thus, lock force. In the illustrated arrangement, the lockposition is when the lock members 2120, 2122 are moved to the left and aportion of the lock members 2120, 2122 are flat against the stopsurfaces 2114 a, 2116 a and the release position is when the lockmembers 2120, 2122 are moved to the right and the edges of the lockmembers 2120, 2122 are contacting the stop surfaces 2114 b, 2116 b.However, this arrangement could also be reversed.

In either arrangement, angles α and β, respectively, are defined by thedifference between the release position and the lock position of thelock members 2120, 2122. Preferably, angle α is different than angle β.In some configurations, angle α is less than angle β. As describedpreviously, in some configurations, the core member can move relative tothe housing while the lock member, in the case of a single lock, movesfrom the release to the lock position or when the lock member moves fromthe lock to the release position. In some cases, the movement of thecore member is related to the angle of the lock member between therelease position and the lock position. As also described previously, insome configurations, the lock force is related to the lock angle, withthe lock force increasing with the lock angle. Thus, a trade-off canexist between providing a high lock force and providing small coremember movement between a release position and a lock position. Theamount of core member movement required to move between the releaseposition and the lock position can be referred to in terms of the lock'sactivation length (amount of core movement) or activation speed (timerequired to transition between release and lock positions), which can beinfluenced by the force tending to move the core member (e.g.,retraction force of the headgear).

In the illustrated arrangement, the first lock stage 2102 is a quickactivation lock, which moves between a release position and a lockposition with less core member 2110 movement or more quickly than thesecond lock stage 2104. The lock member 2120 or core member 2110movement between the release position and the lock position isillustrated by the distance “a” in FIG. 74. The relatively smallmovement distance allows the first lock stage 2102 to move between therelease position and the lock position in response to small adjustmentmovements of the associated interface assembly. In some applications,the focus is on the movement from the release position to the lockposition because the lock 2100 will allow movement of the core member2110 (and extension of the associated headgear) until the lock 2100moves to the lock position. However, movement in the other direction canalso require core member movement and, in some applications, may be acharacteristic of interest.

In use, the user may attempt to microadjust the interface assembly bywiggling or pushing on the mask/interface to compress the seal, therebycausing the headgear to retract or the core member 2110 to move in adirection tending to move the lock member 2120 toward the releaseposition (to the right in FIG. 74). The first lock stage 2102 movesquickly to the lock position once the user removes the pushing forcefrom the mask/interface and allows a preferably small amount ofexpansion of the associated headgear. As a result, the directional lock2100 is responsive to small movements of the mask/interface and locksthe mask/interface very close to the desired adjustment position. Asdiscussed above, the first lock stage 2102 can move quickly to the lockposition due to a relatively small lock angle α. However, the first lockstage 2102 may provide a maximum lock force that is lower than a desiredlock force, which may also be a result of the relatively small lockangle α.

However, the second lock stage 21044 can be a high force lock, which canprovide a desired maximum lock force for the directional lock 2100. Thesecond lock stage 2104 can have a movement of the lock member 2122 orcore member 2110 between the release position and the lock position thatis illustrated by the distance “b” in FIG. 74. In some configurations,the distance “b” is greater than the distance “a” of the first lockstage 2102. As described above, the lock angle β of the second lockstage 2104 can be greater than the lock angle α, which in someconfigurations can result in the second lock stage 2104 having a higherlock force than the first lock stage 2102. Combining the first lockstage 2102 and the second lock stage 2104 can result in a direction lock2100 that is responsive to small adjustment movements of the associatedheadgear/interface, while also providing a lock or yield force that issufficient to address normal or expected operational forces.

In some configurations, the distance “a” is about 1 millimeter or lessto provide for micro-adjustment of the associated headgear/interface.However, in some configurations, the distance “a” can be greater than 1millimeter. The distance “a” can be selected based on a lock distancethat is tolerable for a given application. In other words, the distance“a” can be selected based on the level of micro-adjustment that isnecessary or desirable for a given application. As described above, aninterface assembly can comprise more than one directional lock, such asone on each side of the interface assembly, for example. Accordingly,the total lock distance can be greater than the lock distance of asingle directional lock and, in some cases, can be the sum of theindividual lock distances. The distance “b” can be selected to achieve adesired maximum lock force. In some configurations, the distance “b” canbe at least about twice as great, at least about five times as great, atleast about ten times as great or at least about twenty times as greatas the distance “a”. The ratios of the angles α and β can be the same asor similar to the ratios of the distances “a” and “b”.

FIG. 75 illustrates a force profile 2200 of a headgear or interfaceassembly comprising at least one dual stage directional lock, such asthe directional lock 2100 of FIG. 74. The force profile 2200 can begenerally similar to the force profiles discussed in connection withFIGS. 2-5. Thus, the force profile 2200 includes an initial steep rise2220 illustrating the initial resistance to stretch. The force profilealso includes a substantially flat, generally constant extension curve2222 illustrating further stretch of the headgear and a decline 2224 asthe headgear retracts to fit the user's head. However, in contrast tothe force profiles of FIGS. 2-5, the force profile 2200 includes astepped balanced fit section 2230, which illustrates a transitionbetween the first lock stage 2102 and the second lock stage 2104.

In particular, the balanced fit section 2230 can include a first portion2230 a and a second portion 2230 b. The first portion 2230 a can berelated to the characteristics of the first lock stage 2102 and thesecond portion 2230 b can be related to the characteristics of thesecond lock stage 2104. The second portion 2230 b can also be influencedby resistance offered by the first lock stage 2102 in combination withthe second lock stage 2104. As illustrated, the second portion 2230 b isoffset from the first portion 2230 a by a transition portion 2230 c,which can reflect a transition from the first lock stage 2102 to thesecond lock stage 2104. That is, the offset can be reflective of adifference between the distance “b” and the distance “a” in FIG. 74.

The balance fit section 2230 includes a solid line portion, whichillustrates extension of the headgear up until the balanced fit point2234. The dashed line portion above the balanced fit point 2234illustrates additional extension that would occur in the headgear inresponse to additional forces. In the illustrated arrangement, thebalanced fit point 2234 falls within a capability range of the firstlock stage 2102. That is, the balanced fit point 2234 is less than themaximum lock force of the first lock stage 2102. However, in some cases,such as high therapy pressures, the balance fit point 2234 may be abovethe maximum lock force of the first lock stage 2102 and may fall withinthe second portion 2230 b of the balanced fit section 2230. Preferably,the balance fit point 2234 falls below the maximum lock force of thesecond lock stage 2104. A yield point 2236 can be defined by anintersection of the balanced fit section 2230 and the constant extensioncurve 2222.

An initial activation length 2240 is defined as the extension distancebetween a beginning of the balanced fit section 2230 and the balancedfit point 2234. The initial activation length 2240 can be related to thedistance “a” of the first lock stage 2102. A secondary activation length2242 can be defined as the extension distance between the balanced fitpoint 2234 and the end of the transition portion 2230 c/beginning of thesecond portion 2230 b of the balanced fit section 2230. The secondaryactivation length 2242 can be related to the distance “b” of the secondlock stage 2104. The force profile 2200 is merely an example of a forceprofile that can be provided by a dual stage directional lock, such asthe lock 2100. Directional locks having a variety of different forceprofiles to suit a particular application or desired performancecriteria can be achieved based on the teachings of the presentdisclosure. For example, multiple individual locks of any type disclosedherein can be combined to created dual or multi-stage locks. Theindividual locks can be of the same type or can vary in type within asingle dual or multi-stage lock.

Although certain mechanical directional lock arrangements arespecifically illustrated herein, other mechanical and non-mechanicalmethods and arrangements for achieving a self-fit, large hysteresis ordirectional lock can also be used. For example, electric, piezoelectric,pneumatic, hydraulic or thermomechanical arrangements can be configuredto provide functionality similar to the interface assemblies disclosedherein. In some configurations, such methods or arrangements canselectively grip or release an inelastic core similar to thearrangements disclosed herein.

In one example of an electric arrangement, a solenoid clutch can beemployed to provide a directional lock function. For example, anelectric coil around a plunger can move the plunger when energized. Thismovement can be utilized to directly or indirectly pinch or grip thenon-stretch member of the self-adjust headgear to hold the non-stretchmember. The holding mechanism can release the non-stretch member toallow elongation. The solenoid clutch can be controlled by any suitablearrangement, such as a button. Alternatively, a sensor could determinewhen the headgear is positioned and/or when a CPAP pressure is activatedand the holding mechanism could be activated.

Alternatively, a stepper motor or servo motor could be utilized toactively hold the position of an adjustable member of the headgear, suchas a non-stretch member. Retraction and/or extension can be accomplishedby the motor. In some configurations, an electromagnetic force generatorcould be utilized to act on an adjustable member of the headgear havingmagnetic sections or properties. Retraction could be accomplished by alinear motor. In some configurations, an electro-active polymer can beutilized to create a clutch or pinching mechanism in response to anelectrical current that acts on and holds an adjustable member of theheadgear. Alternatively, an electro-magnetic force can act on a magneticliquid to create a clutch or pinching mechanism that can hold anadjustable member of the headgear.

In an example of a piezoelectric arrangement, a piezoelectric clutch orclamp can be utilized to release free movement of the non-stretchheadgear. Examples of piezo-mechanisms include piezo-membrane (buzzer),diesel engine valves and inkjet nozzles. Each of these mechanisms use apiezo element to create a movement/displacement. Such a piezo-mechanismcould be used directly or to drive a holding clutch to selectively holdan adjustable member of a self-fit headgear. A few piezoelectriccomponents could be configured to create a so-called inchworm motor. Aninchworm motor (or similar) arrangement is specifically useful forlinear motion. Such movement can be utilized in the adjustment of aself-fit headgear arrangement.

In a pneumatic arrangement, a pneumatic cylinder or pneumatic bellowscan operate a clutch or gripping mechanism activated by CPAP pressure oran auxiliary air/gas supply. The clutch or gripping mechanism candirectly or indirectly hold an adjustable member of a self-fit headgear.Similarly, in a hydraulic arrangement, a hydraulic cylinder or bladdercould be utilized to hold an adjustable member of a self-fit headgear.CPAP pressure could be utilized to pressurize the hydraulic fluid, forexample. Alternatively, a piston could be mechanically moved topressurize the hydraulic fluid.

In a thermomechanical arrangement, a thermo-sensitive substance (e.g.,wax) can be utilized to actuate a clutch or holding mechanism forholding an adjustable member of a self-fit headgear. Activation of theclutch or holding mechanism can be driven from contact with or proximityto warmth of the user's skin or another suitable heat source, such as aheated breather tube of the CPAP system. Wax filled cartridges arecommonly used to operate thermostatic valves. The wax expands orcontracts with changing temperatures, which is subsequently transformedinto movement of, for instance, a plunger. In absence of sufficientheat, the clutch can release its grip to allow for fitting of theheadgear to the user. Once the headgear is in place and thethermomechanical clutch is exposed to the heat source, the clutch canengage to hold the headgear from expanding. Another example of athermo-sensitive substance is a bi-metallic member that deforms underthe influence of heat, which displacement can be utilized to activate aholding clutch or lock of the self-fit headgear.

While various embodiments have been described, it should be noted thatany of the adjustment mechanisms can be combined with any of the otherassemblies. In addition, the adjustment mechanisms can be used without abreak-fit assembly and the break-fit assemblies can be used without anadjustment mechanism. Further, any interface (i.e., mask and headgear)can be used with either or both of an adjustment mechanism describedherein and/or a break-fit assembly. The break-fit assembly can includethose described in U.S. Provisional Patent Application No. 61/681,024,filed on Aug. 8, 2012, for example but without limitation, which ishereby incorporated by reference in its entirety.

Although the present invention has been described in terms of a certainembodiment, other embodiments apparent to those of ordinary skill in theart also are within the scope of this invention. Thus, various changesand modifications may be made without departing from the spirit andscope of the invention. For instance, various components may berepositioned as desired. Moreover, not all of the features, aspects andadvantages are necessarily required to practice the present invention.Accordingly, the scope of the present invention is intended to bedefined only by the claims that follow.

What is claimed is:
 1. A patient interface, comprising: a mask andheadgear for securing the mask to a user's face, the headgearcomprising: an elastic portion configured to provide a retraction force;a non-elastic portion configured to be inelastic in comparison to theelastic portion; and a restriction mechanism connected to thenon-elastic portion and to the elastic portion, the restrictionmechanism configured to require a first resistance force to permitelongation of the headgear and a second resistance force in response toretraction of the headgear; wherein the restriction mechanism includes adirectional lock arrangement, the non-elastic portion includes a coremember, and the elastic portion includes an elastic strap, the coremember being connected to the elastic strap and comprising a portionpassing through the directional lock arrangement, the elastic portionproviding a force tending to move the core member through thedirectional lock arrangement; wherein one of the headgear and the maskincludes a conduit that resides in, is carried by, or is formed in theone of the headgear and the mask, the elastic strap being attached toone of a part of the headgear other than the core member and the mask,and the core member including a free end retained within the conduit. 2.The patient interface of claim 1, wherein the directional lockarrangement forms a portion of a side strap of the headgear.
 3. Thepatient interface of claim 2, wherein the elastic strap and at least aportion of the core member form at least a portion of the side strap. 4.The patient interface of claim 1, wherein the core member is connectedat one end to the elastic strap.
 5. The patient interface of claim 1,wherein the first resistance force is larger than the second resistanceforce.
 6. The patient interface of claim 1, wherein in use the firstresistance force is larger than a combined resistance force comprising aCPAP pressure force and a hose drag force.
 7. The patient interface ofclaim 1, wherein in use the second resistance force is smaller than acombined force comprising a CPAP pressure force and a hose drag force.8. The patient interface of claim 1, wherein a cross-sectional dimensionof the core member is in the range of about 0.1 mm to about 8 mm.
 9. Thepatient interface of claim 1, wherein the conduit resides in, is carriedby, or is formed in the headgear.
 10. The patient interface of claim 9,wherein the mask comprises a frame, and the headgear clips onto or intothe frame.
 11. The patient interface of claim 1, wherein the directionallock arrangement comprises first and second lock member mechanisms, theelastic strap comprises a stretch sheath, a middle section of the coremember being housed inside the stretch sheath, and the stretch sheath isconnected to the conduit.
 12. The patient interface of claim 11, whereinthe first or second lock member mechanism is capable of moving relativeto the core member through a range of angles between about 0° to about45°.
 13. The patient interface of claim 11, wherein the stretch sheathor the elastic strap is a braid comprising a non-elastic element suchthat the non-elastic element provides a physical end stop to extensionbefore the braid is plastically deformed.
 14. The patient interface ofclaim 1, wherein the directional lock arrangement is a mechanicaldirectional lock that comprises a housing, a movable lock member withinthe housing and the core member, wherein the housing guides movement ofthe core member, and wherein both the housing and the movable lockmember are formed by a single integrated module.
 15. The patientinterface of claim 1, wherein the directional lock arrangement is amechanical directional lock that comprises a lock module, wherein thelock module, the non-elastic portion and the elastic portion form amodular adjustment assembly.
 16. The patient interface of claim 15,wherein the modular adjustment assembly is connected to a frame of themask.
 17. The patient interface of claim 16, wherein the headgear clipsonto or into the frame.
 18. The patient interface of claim 16, whereinthe frame comprises one or more walls defining a space that receives thelock module.
 19. The patient interface of claim 15, wherein the modularadjustment assembly is connected to a rear portion of the headgearcomprising at least one of a lower rear strap and a crown strap.
 20. Thepatient interface of claim 11, wherein the first and second lock membermechanisms comprise a first lock stage that provides a first lock forceand a second lock stage that provides a second lock force, wherein thesecond lock force is greater than the first lock force.
 21. The patientinterface of claim 20, wherein the first lock stage transforms to agenerally non-elongating type behavior with less elongation movementthan the second lock stage.
 22. The patient interface of claim 1,wherein the directional lock arrangement is a mechanical directionallock comprising a dual stage directional lock comprising two differentlock stages, the two lock stages having different locking behavior orcharacteristics from one another.
 23. The patient interface of claim 22,wherein a first lock stage of the two lock stages is a quick activationlock that moves more quickly between a release position and a lockposition than a second lock stage of the two lock stages.
 24. Thepatient interface of claim 23, wherein the second lock stage is a highforce lock that provides a higher lock or yield force than the firstlock stage.
 25. The patient interface of claim 1, wherein thedirectional lock arrangement is a mechanical directional lock comprisinga housing, the housing defining two lock chambers, each lock chamberhaving a lock member positioned therein, each lock member comprising anopening, and the core member passing through the housing and the openingin each lock member.
 26. The patient interface of claim 25, wherein thelock members are movable between a lock position, in which resistance tomovement of the core member is increased, and a release position, inwhich resistance to movement of the core member is reduced.
 27. Thepatient interface of claim 25, wherein a first lock member is movablebetween a first lock position, in which resistance to movement of thecore member is increased, and a first release position, in whichresistance to movement of the core member is reduced, and a second lockmember is movable between a second lock position, in which resistance tomovement of the core member is increased, and a second release position,in which resistance to movement of the core member is reduced.
 28. Thepatient interface of claim 27, wherein a difference in an angle ordistance between the first lock position and the first release positionis less than a difference in an angle or distance between the secondlock position and the second release position.
 29. The patient interfaceof claim 1, wherein the directional lock arrangement is a mechanicaldirectional lock comprising a housing, a roller ball, a switch, and thecore member.
 30. The patient interface of claim 29, wherein the switchcomprises a magnet and a magnetic member.
 31. The patient interface ofclaim 1, wherein the directional lock arrangement is a mechanicaldirectional lock comprising a housing, an S-shaped friction membercomprising a bendable curve, a washer adjacent the bendable curve, andthe core member passing through an orifice in the S-shaped frictionmember and the washer.
 32. The patient interface of claim 1, wherein thedirectional lock arrangement is a mechanical directional lock comprisinga housing and a core member running through the housing, the housinghaving an interior cavity comprising a spring-loaded clip, the coremember comprising a serrated edge, the spring-loaded clip beingconfigured to interact with the serrated edge.
 33. The patient interfaceof claim 1, wherein the directional lock arrangement is a mechanicaldirectional lock comprising a housing, a washer, and the core member,the housing having an internal cavity configured to have a free movementsurface that is substantially vertical and orthogonal to a longitudinalaxis defined by the core member, and a locking surface that is angledwith respect to the longitudinal axis defined by the core member, thewasher being located within the internal cavity, the core member passingthrough an orifice in the housing and the washer.
 34. The patientinterface of claim 1, wherein the directional lock arrangement is amechanical directional lock comprising a housing, a washer, and the coremember, the housing having an internal cavity, the washer comprising anangled surface and being located within the internal cavity, the coremember passing through an orifice in the housing and the washer.
 35. Thepatient interface of claim 1, wherein the directional lock arrangementis a mechanical directional lock comprising a washer and a rotatablemember disposed within a housing and the core member passing through anorifice in the housing, washer, and rotatable member.
 36. The patientinterface of claim 1, wherein the directional lock arrangement is amechanical directional lock comprising a housing including a resilientlock member with a C-shaped cross-section in an internal cavity and thecore member passing through an orifice in the housing and the resilientlock member.
 37. The patient interface of claim 1, wherein thedirectional lock arrangement is a mechanical directional lock comprisinga housing including a crushable core member in an internal cavity andthe core member passing through an orifice in the housing and thecrushable core member.
 38. The patient interface of claim 1, wherein thedirectional lock arrangement is a mechanical directional lock comprisinga housing having an interior chamber ramped to be larger at a first endthan a second end, a roller ball within the interior chamber, and thecore member passing through an orifice in the housing, the roller ballbeing positioned between a wall of the interior chamber and the coremember.
 39. The patient interface of claim 1, wherein the directionallock arrangement is a mechanical directional lock comprising a housinghaving a conical interior chamber, the core member, and a reversiblycompressible collet member around the core member.
 40. The patientinterface of claim 1, wherein the directional lock arrangement is amechanical directional lock comprising a housing, a lock member coupledto the housing by a living hinge, and the core member, the housing andlock member comprising openings through which the core member passes,the lock member being moveable between a release position and a lockposition.